<html><head><meta name="color-scheme" content="light dark"></head><body><pre style="word-wrap: break-word; white-space: pre-wrap;">%\iffalse
% !TEX encoding = UTF-8 Unicode
% !TEX TS-program = pdflatex
%&lt;*internal&gt;
\begingroup
%^^A Load the docstrip package (DO NOT USE \input{...})
\input docstrip.tex
\keepsilent
%^^A\usedir{tex/latex/graphpaper}
%^^A insert this text at the beginning of the generated file
\preamble
 ________________________________________
 The graphpaper class for generating several types of graph paper
 Copyright (C) 2020 - 2022 C. Beccari &amp; F. Biccari
 All rights reserved
 
 License information appended
 
\endpreamble
%^^A insert this text at the end of the generated file
\postamble
Copyright (C) 2020 - 2022 Claudio Beccari &amp; Francesco Biccari

Distributable under the LaTeX Project Public License,
version 1.3c or higher (your choice). The latest version of
this license is at: http://www.latex-project.org/lppl.txt

This work is "author-maintained".

This work consists of this file graphpaper.dtx,
and the derived files graphpaper.cls and graphpaper.pdf.

\endpostamble
%^^A
%^^A DocStrip can silently overwrite an already existing cls file 
\askforoverwritefalse
%^^A
%^^A Generates the cls file from the dtx file, stripping out all
%^^A the documentation. The option "class" tells to DocStrip to 
%^^A extract only the code marked with the "class" tag.
\generate{\file{graphpaper.cls}{\from{graphpaper.dtx}{class}}}
%
\def\tmpa{plain}
\ifx\tmpa\fmtname\endgroup\expandafter\bye\fi
\endgroup
%&lt;/internal&gt;
%\fi
%^^A %
%^^A ---------------------------------------------------------------------- 
%^^A Here starts the second part
%^^A ProvidesFile must be (more or less) the first command for a class dtx.
%^^A It populates the variables \filename, \filedate, and \fileversion
%^^A
% \iffalse
%&lt;*driver&gt;
\ProvidesFile{graphpaper.dtx}
%&lt;/driver&gt;
%&lt;class&gt;\NeedsTeXFormat{LaTeX2e}[2021-10-10]
%&lt;class&gt;\ProvidesClass{graphpaper}%
%&lt;*class&gt;
   [2022-04-23 1.1 A LaTeX class to generate several types of graph papers]
%&lt;/class&gt; 
%&lt;*driver&gt;
\documentclass[11pt,a4paper]{ltxdoc}
\usepackage[T1]{fontenc}
\usepackage{lmodern}
\usepackage[a4paper,lines=50]{geometry}
\usepackage{multicol}
\hfuzz 10pt
\let\originalmeta\meta
\renewcommand\meta[1]{{\normalfont\originalmeta{#1}}}
\renewcommand\marg[1]{\texttt{\{\meta{#1}\}}}
\newcommand\Marg[1]{\texttt{\{#1\}}}
\newcommand\opz[1]{\texttt{[\meta{#1}]}}
\newcommand\Opz[1]{\texttt{[#1]}}
\newcommand\amb[1]{\texttt{\slshape#1}}\let\env\amb
\renewcommand\cs[1]{{\normalfont\ttfamily\char92#1}}
\newcommand\Benv[1]{\texttt{\char92begin\{#1\}}}
\newcommand\Eenv[1]{\texttt{\char92end\{#1\}}}
\newcommand\eTeX{$\varepsilon$-\TeX}
\providecommand\prog{}
\renewcommand\prog[1]{\textsf{#1}}
\newcommand\pack[1]{\texttt{\itshape#1}}
\newcommand\class[1]{\texttt{#1}}
%
\newenvironment{ttsintassi}{\begin{lrbox}{0}
\minipage{\dimexpr\linewidth-2\fboxrule-2\fboxsep}\ttfamily\obeylines}%
{\endminipage\end{lrbox}\center\fbox{\box0}\endcenter}
\let\ttsyntax\ttsintassi \let\endttsyntax\endttsintassi
%
\usepackage{color}
\definecolor{sfondoblu}{rgb}{0.94,0.97,1}
\usepackage{listings}
\lstset{language=[LaTeX]TeX,
	basicstyle=\footnotesize\ttfamily,
	keywordstyle=\color{blue}\bfseries,
	commentstyle=\color{gray},
	backgroundcolor=\color{sfondoblu},
	frameround=tttt,
	frame=tlrb,
	escapechar=|,
	morekeywords={bilinear, semilogx, semilogy, loglog, polar, logpolar, smith, setgridcolor, setmajorlinethickness, setmediumlinethickness, setminorlinethickness, setminimumdistance, setxside, setyside, customcode},
	columns=flexible
}
\begin{document}
\GetFileInfo{graphpaper.dtx}
\title{Documentation of the \class{graphpaper} \LaTeX\ class}
\author{Claudio Beccari \and Francesco Biccari\thanks{Corresponding author: biccari@gmail.com}}
\date{Version number \fileversion; last revised on \filedate.}
\maketitle
\setcounter{tocdepth}{2}
\renewcommand{\columnseprule}{0.4pt}
\setlength{\columnsep}{1.5cm}

\addtocontents{toc}{\protect\begin{multicols}{2}}
{\small
\tableofcontents}

\DocInput{graphpaper.dtx}
\addtocontents{toc}{\protect\end{multicols}}
\end{document}
%&lt;/driver&gt;
% \fi
%^^A \CheckSum{100}
%\begin{abstract}
% This document describes how to use the \LaTeX\ document class \class{graphpaper}.
% It allows to print several types of graph papers: bilinear,
% semilogarithmic, bilogarithmic, polar, Smith charts.
%\end{abstract}
%
%\section{Legal terms}
% This file is part of the |graphpaper| bundle.
% 
% This work may be distributed and/or modified under the
% conditions of the \LaTeX\ Project Public License, either version 1.3c
% of this license or (at your option) any later version.
% The latest version of this license is at:
%   http://www.latex-project.org/lppl.txt
%
% This work has the LPPL maintenance status ``maintained''.
% 
% This work consists of this file graphpaper.dtx,
% and the derived files graphpaper.cls and graphpaper.pdf.
%
% The list of derived (unpacked) files belonging to the distribution 
% and covered by the LPPL is contained in the README file.
% 
%\section{Installation}
% The simplest way to install \class{graphpaper} is by the package manager of your \TeX\
% distribution (\TeX\ Live or MiK\TeX). For manual installation see the README file.
%
%
% \newpage
% \section{How to use graphpaper}
% \label{sec:howto}
%
% \class{Graphpaper} is a \LaTeX\ class and it is loaded as usual:
%
% \iffalse
%&lt;*example&gt;
% \fi
\begin{lstlisting}
\documentclass|\opz{options}|{graphpaper}
\end{lstlisting}
% \iffalse
%&lt;/example&gt;
% \fi
%
% It has three class options to specify the paper format:
% \texttt{a4paper} (default), \texttt{a3paper}, \texttt{letterpaper}.
% The paper orientation cannot be changed and it is always set
% to landscape.
% 
% \class{Graphpaper} provides the following commands (to be used 
% inside the body of the document) in order to compose graph papers. 
% At the end of the execution of these commands, a new page
% is always started.
% 
% \iffalse
%&lt;*example&gt;
% \fi
\begin{lstlisting}
\bilinear

\semilogx|\marg{decades along x}|

\semilogy|\marg{decades along y}|

\loglog|\opz{0/1}||\marg{decades along x}||\marg{decades along y}|

\polar

\logpolar|\marg{decades along radius}|

\smith
\end{lstlisting}
% \iffalse
%&lt;/example&gt;
% \fi
% The commands \cs{bilinear}, \cs{semilogx}, and \cs{semilogy} are self
% explanatory. 
% The optional parameter in the \cs{loglog} command chooses wether the
% decade length along the abscissa and ordinate axes must have the same
% dimension. It can assume the value 0 (free dimensions) or 1 (same
% dimensions), 0 being the default.
% The commadns \cs{polar}, \cs{logpolar}, \cs{smith} are used to plot
% polar, logpolar, and Smith chart graph papers. The mandatory argument
% of \cs{logpolar} specifies the number of decades.
%
% There are several commands to change the appearance of the graph papers.
% They must be inserted before the graph paper command which we want they
% affect.
% 
% The following ones are specific to bilinear, semilog and loglog papers
% only:
% \iffalse
%&lt;*example&gt;
% \fi
\begin{lstlisting}
\setxside|\marg{length}|

\setyside|\marg{length}|

\setminimumdistance|\marg{length}|
\end{lstlisting}
% \iffalse
%&lt;/example&gt;
% \fi
% \cs{setxside} and \cs{setyside} allow to specify the dimensions of the
% rectangle of the grid. The default values are (260\,mm, 180\,mm) for
% A4 paper, (250\,mm, 190\,mm) for letter paper, and (380\,mm, 280\,mm)
% for A3 paper.
% 
% \cs{setminimumdistance} specifies the minimal optical distance 
% between two lines. Default is 1\,mm. In this way, the number of
% subdivision is automatically composed.
%
% The following commands are instead general settings for all graph
% papers:
% \iffalse
%&lt;*example&gt;
% \fi
\begin{lstlisting}
\setgridcolor|\marg{color}|

\setmajorlinethickness|\marg{length}|

\setmediumlinethickness|\marg{length}|

\setminorlinethickness|\marg{length}|

\customcode|\opz{0/1}\marg{picture environment commands}|
\end{lstlisting}
% \iffalse
%&lt;/example&gt;
% \fi
%
% \cs{setgridcolor} sets the color of the grid. The argument must be a
% color defined or predefined by the color or |xcolor| package. The
% default color is the typical red-orange color used in many graph papers,
% Pantone 2011 U corresponding  to RGB (250,153,89).
% 
% \cs{setmajorlinethickness}, \cs{setmediumlinethickness},
% \cs{setminorlinethickness} can be used to change the thickness of the
% lines. The default values  are 1\,pt, 0.6\,pt, 0.25\,pt, respectively.
%
% \cs{customcode} accepts all the commands accepted by the picture
% environment.  This snippet of code is inserted inside the picture
% environment used to draw the subsequent graph paper.
% The origin of the coordinate system in the case of rectangular graph
% papers is the lower left vertex. The \cs{unitlength} is set to 1\,mm. 
% For circular plots (both polar and Smith) the origin is in the center
% of the circle and the \cs{unitlength} is set to 1/140 of the paper height
% currently in use.
%
% The \cs{customcode} command can be used, for example, to add a logo
% or to draw on the graph paper.
% Its optional argument is by default set to 0. If it is set to 1, the
% content of the \cs{customcode} is erased after its usage in a
% graphpaper.
% 
%  
%\StopEventually{}
%
%\iffalse
%&lt;*class&gt;
%\fi
%\clearpage
%\section{The implementation}
% This class file has been already identified by the commands extracted
% by the |DocStrip| package, during  the |.dtx| file compilation.
% Therefore the commands \cs{NeedsTeXFormat} and \cs{ProvidesClass} are
% already present in the |.cls| file.
%
% \subsection{Loaded packages, class options, and initial settings}
% The |xkeyvalue| package is used in order to define the class options:
%    \begin{macrocode}
\RequirePackage{xkeyval}
%    \end{macrocode}
% Three class options are implemented and they allows only to change the 
% paper format (A4, A3, letter). The orientation of the paper is fixed
% to landscape.
%
%    \begin{macrocode}
\def\GP@paper{1}
\define@key[GRP]{}{a4paper}[]{\PassOptionsToPackage{a4paper}{geometry}}
\define@key[GRP]{}{letterpaper}[]{\PassOptionsToPackage{letterpaper}{geometry}%
  \def\GP@paper{2}}
\define@key[GRP]{}{a3paper}[]{\PassOptionsToPackage{a3paper}{geometry}%
  \def\GP@paper{3}}
\DeclareOptionX*{\ClassError{graphpaper}{Option '\CurrentOption'%
  \MessageBreak is not valid}{Remove '\CurrentOption' %
  from class options}}
\ProcessOptionsX[GRP]&lt;&gt;
%    \end{macrocode}
%
% The class is based on the \class{article} class. The default paper
% is A4.
%    \begin{macrocode}
\LoadClass[a4paper,11pt]{article}
%    \end{macrocode}
%
% Some packages are loaded. \pack{euclideangeometry} loads \pack{curve2e} 
% which in turns loads \pack{pict2e}; all of them are \env{picture}
% environment extensions.
%    \begin{macrocode}
\RequirePackage[landscape]{geometry}
\RequirePackage{euclideangeometry,graphicx,xcolor}
%    \end{macrocode}
%
% Default line color (Pantone 2011~U).
%    \begin{macrocode}
\definecolor{gridcolor}{RGB}{250,153,89}
%    \end{macrocode}
%
% Default thickness of the lines used for main divisions and subdivisions.
% The ISO-UNI standards prescribe a geometric progression with $\sqrt{2}$
% ratio, but it is not respected here.
% It must be keep in mind also that a safe minimum thickness for an offset
% monochromatic printer is about 0.25\,pt, whereas a safe minimum
% thickness for a laser printer is about 0.5\,pt.
%    \begin{macrocode}
\newlength\lwa
\setlength{\lwa}{1pt}
\newlength\lwb
\setlength{\lwb}{0.6pt}
\newlength\lwc
\setlength{\lwc}{0.25pt}
%    \end{macrocode}
%
% Minimum distance between two subdivision lines. A necessary parameter
% for automatic choice of number of subdivisions. Default 1\,mm.
%    \begin{macrocode}
\newlength\mindistanceunit
\setlength{\mindistanceunit}{1mm}
%    \end{macrocode}
%
% Definition of the width and height of the main rectangle within which
% the bilinear, semilog and loglog grid is composed.
%    \begin{macrocode}
\newlength\xsideunit
\newlength\ysideunit
\if\GP@paper1 
  \setlength{\xsideunit}{260mm}
  \setlength{\ysideunit}{180mm}
\fi
\if\GP@paper2 
  \setlength{\xsideunit}{250mm}
  \setlength{\ysideunit}{190mm}
\fi
\if\GP@paper3 
  \setlength{\xsideunit}{380mm}
  \setlength{\ysideunit}{280mm}
\fi
%    \end{macrocode}
%
%\subsection{Rectangular graph papers}
%
% As we will see below, the commands to compose the bilinear, semilog
% and loglog graph papers are just proper calls of the low-level command
% \cs{carta}. 
%
%\subsubsection{Service macros for rectangular graph papers}
% 
% First of all, four macros are defined. They are used by the
% \cs{carta} service command only. 
%
% Two of them are simply two identical classical |whiledo| commands:
% the first cycles on the counter \cs{J} while the second one on the
% counter \cs{K}.
% They are two because in this way two nested |whiledo| commands can be
% implemented.
% These \cs{WhileDo} commands have four parameters: 
% 1. the incremental step of the counter between cycles (default 1); 
% 2. the initial value of the counter; 
% 3. the final value of the counter; 
% 4. the code to execute at each cycle.
%    \begin{macrocode}
\newcount\J
\newcount\K

\newcommand\WhileDoOne[4][1]{%
	\J=#2 \fpdowhile{\J=&lt;#3 }{#4\advance\J by #1\relax}}

\newcommand\WhileDoTwo[4][1]{%
	\K=#2 \fpdowhile{\K=&lt;#3 }{#4\advance\K by #1\relax}}
%    \end{macrocode}
%
%
% The other two commands are used to draw a periodic set of equidistant
% lines in log scale.
% These two commands are practically identical, the only difference is
% that they act on different axes. 
% These commands have six parameters: 
% 1. number of lines to draw (distance between these lines is the fifth
% parameter);
% 2. value at which the first line must be drawn (x-value for vertical
% lines, y-value for horizontal lines);
% 3. thickness;
% 4. tick length;
% 5. distance between two lines (typically the length of a decade:
% y-decade for horizontal lines, x-decade for vertical lines);
% 6. line length (typically the length of the graph paper sides:
% x-side for horizontal lines and y-side for vertical lines).
%
%    \begin{macrocode}
\newcommand\hlines[6]{%
\multiput(-#4,\fpeval{ln(#2) * #5 / ln(10)})(0,#5){#1}%
{\linethickness{#3}\line(1,0){\fpeval{#6 + 2*#4}}}%
}

\newcommand\vlines[6]{%
\multiput(\fpeval{ln(#2) * #5 / ln(10)},-#4)(#5,0){#1}%
{\linethickness{#3}\line(0,1){\fpeval{#6 + 2*#4}}}%
}
%    \end{macrocode}
%
%\subsubsection{Command for rectangular graph papers}
% 
% Here starts the definition of the \cs{carta} command. Its syntax is
%\begin{ttsyntax}
%\cs{carta}\opz{0 or1}\marg{no. x decades}\marg{no. of y decades}
%\end{ttsyntax}
% If an axis has zero decades, the scale is linear.
% For example, \cs{carta}\Marg{0}\Marg{0} composes a bilinear graph
% paper, \cs{carta}\Marg{2}\Marg{0} composes a semilog graph paper with
% linear y-axis and two decades along x-axis, and so on.
% Its optional argument can be 0 or 1. If it is set to 0, and both the
% numbers of decades are greater than zero (which means the resulting
% graph paper is loglog), then the length of x-axis and y-axis decades
% are set to be equal.
%
% Declaration of the command and its arguments.
%    \begin{macrocode}
\NewDocumentCommand{\carta}{O{0} m m}{%
%    \end{macrocode}
%
% Typographical settings and definition of the main features of the 
% graphpaper. \cs{xlength} and \cs{ylength} represent the lengths,
% expressed in mm, of the rectangle dimensions. \cs{minimumdistance}
% is the minimum distance at which two subdivision lines can be drawn.
%    \begin{macrocode}
\newpage
\parindent=0pt
\pagestyle{empty}%
\color{gridcolor}%
\setlength{\unitlength}{1mm}%
\def\ticklength{2}
\def\minorticklength{1.2}
\def\minimumdistance{\fpeval{(\mindistanceunit/1mm)}}
\def\xlength{\fpeval{round(round(\xsideunit/1cm) * 10)}} 
\def\ylength{\fpeval{round(round(\ysideunit/1cm) * 10)}}
%    \end{macrocode}
%
% \cs{xlinsq} and \cs{ylinsq} represent the number of big divisions 
% (cm) on horizontal and vertical axes for linear scales, respectively. 
%    \begin{macrocode}
\def\xlinsq{\inteval{\xlength/10}}
\def\ylinsq{\inteval{\ylength/10}}
%    \end{macrocode}
%
% Implementation of the same decade length between x-axis and y-axis
% for loglog graph paper. This is obtained properly changing the 
% values of \cs{xlength} and \cs{ylength}, making them equal.
%    \begin{macrocode}
\edef\decx{#2}% decades along x
\edef\decy{#3}% decades along y
\unless\ifnum#2=0 \unless\ifnum#3=0 \ifnum#1=1%
\fptest{\decx/\decy &lt; \xlength/\ylength}%
{\def\xlength{\fpeval{\ylength*\decx/\decy}}}
{\def\ylength{\fpeval{\xlength*\decy/\decx}}}
\fi\fi\fi
%    \end{macrocode}
%
% Using the values of the paper width and height together with the
% length of the graph paper rectangle sides, the margins are calculated
% and passed to the geometry package in order to center the grid with
% respect to the page.
%    \begin{macrocode}
\ifcsname ml\endcsname\relax\else\newlength\ml\fi
\ifcsname mr\endcsname\relax\else\newlength\mr\fi
\ifcsname mt\endcsname\relax\else\newlength\mt\fi
\ifcsname mb\endcsname\relax\else\newlength\mb\fi
\unless\ifcsname mr\endcsname\newlength\mr\fi
\unless\ifcsname mt\endcsname\newlength\mt\fi
\unless\ifcsname mb\endcsname\newlength\mb\fi
\setlength{\ml}{\fpeval{(\paperwidth/1mm - \xlength)/2}mm}
\setlength{\mr}{\fpeval{(\paperwidth/1mm - \xlength)/2}mm}
\setlength{\mt}{\fpeval{(\paperheight/1mm - \ylength)/2}mm}
\setlength{\mb}{\fpeval{(\paperheight/1mm - \ylength)/2}mm}
\newgeometry{left=\ml,right=\mr,top=\mt,bottom=\mb}
%    \end{macrocode}
%
% Here starts the drawing of the graph paper by the |picture| environment.
%    \begin{macrocode}
\begin{picture}(\xlength,\ylength)
%    \end{macrocode}
%
% If the horizontal axis is linear, vertical lines are drawn by
% simple \cs{multiput} commands. Otherwise, if the scale is logarithmic,
% the vertical lines are drawn by the \cs{vlines} command defined above.
%    \begin{macrocode}
\ifnum#2=0\relax
% vertical lines on linear abscissa. Main lines every 10 mm.
% Second level lines every 5 mm, Third level lines every 1 mm,
% according to the \minimumdistance value
  \multiput(0,0)(10,0){\inteval{\xlinsq + 1}}{%
    \linethickness{\lwa}\squarecap\line(0,1){\ylength}}
  \ifnum\fpeval{\minimumdistance &lt;= 5}=1
  \multiput(5,0)(10,0){\xlinsq}{%
    \linethickness{\lwb}\line(0,1){\ylength}}\fi
  \ifnum\fpeval{\minimumdistance &lt;= 1}=1
  \multiput(0,0)(1,0){\xlength}{%
    \linethickness{\lwc}\line(0,1){\ylength}}\fi
\else
  % vertical lines on log abscissa
  \edef\decxx{\fpeval{\decx + 1}}%
  \edef\xstep{\fpeval{\xlength / \decx}}
  % main lines: one for each decade (10) plus one at the end
  \vlines{\decxx}{1}{\lwa}{\ticklength}{\xstep}{\ylength}
  % second-level lines: one every unit (1), for each decade
  \WhileDoOne{2}{9}{\vlines{\decx}{\J}{\lwb}{%
    \minorticklength}{\xstep}{\ylength}}
  % third-level lines: for each decade (10) and for each unit (1):
  % 20, 10, 5, 2 are progressively tested and adopted if the distance
  % between two subsequent nearest lines is less to \minimumdistance  
  \WhileDoTwo{1}{9}{%
    \edef\xmindivfloat{%
      \fpeval{(\K+1)*(1-10^-(\minimumdistance/\xstep))}}
    % xmindiv corresponds to 1/20 of unit
    \def\xmindiv{20}
    % xmindivfloat corresponds to the distance of two
    % subdivision with respect to the unit
    \ifnum\fpeval{\xmindivfloat &lt;= 0.5}=1 \def\xmindiv{10}\fi
    \ifnum\fpeval{\xmindivfloat &lt;= 0.2}=1 \def\xmindiv{4}\fi
    \ifnum\fpeval{\xmindivfloat &lt;= 0.1}=1 \def\xmindiv{2}\fi
    \ifnum\fpeval{\xmindivfloat &lt;= 0.05}=1 \def\xmindiv{1}\fi
    \ifnum\fpeval{\xmindiv == 20}=1\relax
    \else\WhileDoOne[\xmindiv]{\xmindiv}{19}{%
      \vlines{\decx}{(\K+\J/20)}{\lwc}{0}{\xstep}{\ylength}}\fi}
\fi
%    \end{macrocode}
%
% If the vertical axis is linear, horizontal lines are drawn by
% simple \cs{multiput} commands. Otherwise, if the scale is logarithmic,
% the horizontal lines are drawn by the \cs{hlines} command defined above.
%    \begin{macrocode}
\ifnum#3=0\relax
% horizontal lines on linear ordinates. Main lines every 10 mm.
% Second level lines every 5 mm, Third level lines every 1 mm,
% according to the \minimumdistance value
  \multiput(0,0)(0,10){\inteval{\ylinsq + 1}}{%
    \linethickness{\lwa}\squarecap\line(1,0){\xlength}}
  \ifnum\fpeval{\minimumdistance &lt;= 5}=1
  \multiput(0,5)(0,10){\ylinsq}{%
   \linethickness{\lwb}\line(1,0){\xlength}}\fi
  \ifnum\fpeval{\minimumdistance &lt;= 1}=1
  \multiput(0,0)(0,1){\ylength}{%
    \linethickness{\lwc}\line(1,0){\xlength}}\fi
\else
  % horizontal lines on log ordinates
  \edef\decyy{\fpeval{\decy + 1}}%
  \edef\ystep{\fpeval{\ylength / \decy}}
  % main lines: one for each decade (10) plus one at the end
  \hlines{\decyy}{1}{\lwa}{\ticklength}{\ystep}{\xlength}
  % second-level lines: one every unit (1), for each decade
  \WhileDoOne{2}{9}{\hlines{\decy}{\J}{\lwb}{%
    \minorticklength}{\ystep}{\xlength}}
  % third-level lines: for each decade (10) and for each unit (1):
  % 20, 10, 5, 2 are progressively tested and adopted if the distance
  % between two subsequent nearest lines is less to \minimumdistance   
  \WhileDoTwo{1}{9}{\edef\ymindivfloat{%
   \fpeval{(\K+1)*(1-10^-(\minimumdistance/\ystep))}}
	% ymindiv corresponds to 1/20 of unit
	\def\ymindiv{20}
	% ymindivfloat corresponds to the distance of two subdivisions
	% with respect to the unit
	\ifnum\fpeval{\ymindivfloat &lt;= 0.5}=1 \def\ymindiv{10}\fi
	\ifnum\fpeval{\ymindivfloat &lt;= 0.2}=1 \def\ymindiv{4}\fi
	\ifnum\fpeval{\ymindivfloat &lt;= 0.1}=1 \def\ymindiv{2}\fi
	\ifnum\fpeval{\ymindivfloat &lt;= 0.05}=1 \def\ymindiv{1}\fi
	\ifnum\fpeval{\ymindiv == 20}=1\relax
	\else\WhileDoOne[\ymindiv]{\ymindiv}{19}{%
	  \hlines{\decy}{(\K+\J/20)}{\lwc}{0}{\ystep}{\xlength}}\fi}
\fi
%    \end{macrocode}
%
% Custom code provided by the user. After executing the code to compose
% the rectangular graph paper and the user custom code, the latter is
% reset if the \cs{GP@customcodereset} is true.
%    \begin{macrocode}
\GP@custom
\end{picture}
\ifGP@customcodereset\def\GP@custom{}\fi}
%    \end{macrocode}
%
%
%
%\subsection{Circular graph papers}
%
% The \class{Graphpaper} class provides commands to draw three different
% circular graph papers: linear polar chart, log polar chart, Smith chart. 
%
%\subsubsection{Service macros for Smith charts}
% 
% Here follows a list of service macros used by circular graph papers.
%
% Definition of the counter \cs{I}, used both in polar paper and Smith chart.
%    \begin{macrocode}
\newcount\I
%    \end{macrocode}
%
% |Rbox| composes a tick and a label in a rotated box. It is used to
% compose the ticks and labels along the external circle of circular
% graph papers. It accepts three arguments: The first one is
% optional and represents
% the angle of rotation (default 0); the second one is optional too,
% it is inserted by round parentheses, and it represents the position of the
% box which can be given in cartesian $(x,y)$ or polar coordinates $(\theta:\rho)$
% (default 0:0); the third one is mandatory and
% contains the label.
%    \begin{macrocode}
\NewDocumentCommand\Rbox{O{0} D(){0:0} m}{%
    \fptest{#1&gt;=0}{\edef\RotLab{\fpeval{#1-90}}}{\edef\RotLab{\fpeval{#1+90}}}%
    \put(#2){\color{black}\segment(0,0)(#1:1)\put(#1:1){%
            \rotatebox{\RotLab}{\makebox(0,0)[c]{%
                    \fptest{#1&gt;=0}{\Pbox[b]}{\Pbox[t]}{\scriptstyle#3}[0]}}%
        }%
    }\ignorespaces}
%    \end{macrocode}
%
% |\Xcircle| macro (used only for Smith charts) assumes that the scale
% factor |\Scala| ($s$) has already been defined and it takes only one
% mandatory parameter ($x$). It draws a circle with
% center $(sx/(x+1),0)$ and radius $s/(x+1)$. ($x$ represents the real
% part (resistance) of the normalised impedance.)
%    \begin{macrocode}	
\NewDocumentCommand\Xcircle{m}{%
	\edef\Czero{0,0}\edef\Rzero{\Scala}%
	\edef\Rdue{\fpeval{1/(#1+1)*\Scala}}%
	\edef\Cdue{\fpeval{\Rzero-\Rdue},0}%
	\Circlewithcenter\Cdue radius\Rdue\ignorespaces}
%    \end{macrocode}
%
% |\Ycircle| macro (used only for Smith charts) assumes that the scale 
% factor |\Scala| ($s$) has already been defined.
% It assumes that the circle diameter is 100|\unitlength|s long and it
% takes only one
% mandatory parameter ($y$). It draws an arc of a circle with
% center $(s,s/y)$, starting point at $(s,0)$ (and therefore radius 
% $s/y$) and with an angle calculated in order to have the end point on
% the external circle. ($y$ represents the imaginary part (reactance) 
% of the normalised impedance.) 
%    \begin{macrocode}
\NewDocumentCommand\Ycircle{m s}{%
	\edef\Czero{0,0}\edef\Rzero{\Scala}% external circle center and radius 
	\edef\Rdue{\fpeval{\Scala/abs(#1)}}% Small circle radius
	\edef\Cdue{\Rzero,\fpeval{\Scala/#1}}% Small circle center
	\edef\Cuno{\Rzero,0}% First intersection point
	\ModAndAngleOfVect\Cdue to\Mod and\Alfa % Small circle center polar coordinates  
	\IntersectionOfLines(\Czero)(\Cdue)and(\Cuno)(\fpeval{\Alfa+90}:1)to\Inter
	\SymmetricalPointOf\Cuno respect\Inter to\Idue
	\ModAndAngleOfVect\Idue to\Mdue and\Adue
	\SubVect\Cdue from\Idue to\IIdue
	\ModAndAngleOfVect\IIdue to\Mod and\Alfa
	\fptest{#1&gt;0}{\edef\Alfa{\fpeval{270-\Alfa}}\Arc(\Cdue)(\Idue){\Alfa}}%
	{\edef\Alfa{\fpeval{270+\Alfa}}\Arc(\Cdue)(\Cuno){\Alfa}}%
	\IfBooleanT{#2}{\Rbox[\Adue](\Idue){\color{black}#1}}\relax
	\ignorespaces}
%    \end{macrocode}
%
% The following two macros are used to compose the resistance axis 
% below the Smith chart.
%
% |CalcRxx| macro (used only for Smith charts) assumes that the scale 
% factor |Scala| ($s$) has already been defined. 
% First, it calculates the reflection coefficient 
% $\Gamma = s \frac{x-1}{x+1}$ from resistance $x$.
% A tick and a label are inserted for this value of $x$. 
%    \begin{macrocode}
\newcommand\CalcRxx[1]{%
	\edef\Rxx{\fpeval{\Scala*(#1 - 1)/(#1 + 1)}}%
	\segment(\Rxx,\LowResZero)(\Rxx,\LowResUno)\relax
	\Pbox(\Rxx,\LowResUno)[t]{$\color{black}\scriptsize#1$}[0]\ignorespaces}
%    \end{macrocode}
%
% |GradResist| macro (used only for Smith charts) 
% draws the graduated axis for resistance and executes the |CalcRxx|
% for several values of resistance in order to compose the ticks and
% the labels.
%    \begin{macrocode}
\newcommand\GradResist[1]{%
    \color{black}
	\edef\LowResZero{-#1}\edef\LowResUno{\fpeval{\LowResZero-1}}%
	\I=0\edef\Auxx{0}\relax
	\fpdowhile{\I&lt;=10}{\CalcRxx{\Auxx}%
		\advance\I by1\edef\Auxx{\fpeval{\Auxx+0.1}}\ignorespaces}
	\CalcRxx{1.5}\I=2\edef\Auxx{2}\relax
	\fpdowhile{\I&lt;=9}{\CalcRxx{\Auxx}%
		\advance\I by1\edef\Auxx{\fpeval{\Auxx+1}}\ignorespaces}
	\CalcRxx{15}\CalcRxx{30}%
	\edef\Rxx{\Scala}%
	{\segment(-\Rxx,\LowResZero)(\Rxx,\LowResZero)%
		\segment(\Rxx,\LowResZero)(\Rxx,\LowResUno)%
		\Pbox(\Rxx,\LowResUno)[t]{\infty}[0]}}
%    \end{macrocode}
%
% |GradPolar| macro (used only for polar charts) 
% draws the graduated axis for log polar charts.
%    \begin{macrocode}
\newcommand{\GradPolar}[1]{%
    \color{black}
    \edef\yline{\fpeval{-1.2 * \Scala}}
    \linethickness{\lwa}
    \segment(-\Scala,\yline)(\Scala,\yline)
    \edef\ytickstart{\yline}
    \edef\ytickstop{\fpeval{\yline-2}}
    \edef\yytickstop{\fpeval{\yline-1}}
    \segment(\Scala,\ytickstart)(\Scala,\ytickstop)
    \segment(-\Scala,\ytickstart)(-\Scala,\ytickstop)
    \fptest{#1=0}{%
        \segment(0,\ytickstart)(0,\ytickstop)
        \edef\plstep{\fpeval{\Scala/10}}
        \linethickness{\lwb}
        \multiput(\plstep,\yline)(\plstep,0){9}{\line(0,-1){1}}
        \multiput(-\plstep,\yline)(-\plstep,0){9}{\line(0,-1){1}}%
    }{%
    \I=0
    \fpwhiledo{\I&lt;#1}{%
        \linethickness{\lwa}
        \edef\xtick{\fpeval{\I*\Scala/#1}}
        \segment(\xtick,\ytickstart)(\xtick,\ytickstop)
        \segment(-\xtick,\ytickstart)(-\xtick,\ytickstop)
        \J=2
        \fpwhiledo{\J&lt;=9}{%
            \linethickness{\lwb}
            \edef\xtick{\fpeval{\Scala/#1 * (\I + ln(\J)/ln(10))}}
            \segment(\xtick,\ytickstart)(\xtick,\yytickstop)
            \segment(-\xtick,\ytickstart)(-\xtick,\yytickstop)
            \advance\J by1\relax}
        \advance\I by1\relax}}
}
%    \end{macrocode}
%
%
%\subsubsection{Polar graph papers}
%
% The polar graph papers are composed by the command \cs{PolarChart}.
% The syntax is
%\begin{ttsyntax}
% \cs{PolarChart}\opz{diameter}\marg{decades}
%\end{ttsyntax}
% where \meta{diameter} is the dimension (plus some extra space for
% labels and margins) of the polar chart. Its default value 
% corresponds to the \cs{paperheight} (the minimum dimension of the
% paper).
% The mandatory parameter \meta{decades} must be an integer number.
% Its value corresponds to the number of decades of the radial
% coordinate for the log polar graph paper.
% If its value is zero, the chart is linear.
% The maximum number of allowed decades is set by the macro \cs{NDecMax}:
% its default value is~2.
%
% Declaration of the command and its arguments.
%    \begin{macrocode}
\NewDocumentCommand\PolarChart{O{\paperheight} m}{%
%    \end{macrocode}
%
% Typographical settings and definition of the main features of the graphpaper.
% \cs{xlength} and \cs{ylength} represent the lengths of the rectangle 
% dimensions in which the polar graph is plot. 
% The origin of the coordinate system is in the center of the page.
%    \begin{macrocode}
	\newpage
	\parindent=0pt
	\pagestyle{empty}%
	\ifcsname pmargin\endcsname\relax\else\newlength\pmargin\fi
	\setlength{\pmargin}{20pt}
	\newgeometry{left=\pmargin,right=\pmargin,top=\pmargin,bottom=\pmargin}
	\def\factor{140}
	\unitlength=\fpeval{#1/\factor}pt
	\def\xlength{\fpeval{(\textwidth-0.01pt)/\unitlength}} 
	\def\ylength{\fpeval{(\textheight-0.01pt)/\unitlength}}
	\begin{picture}(\xlength,\ylength)%
	    (\fpeval{-\xlength/2},\fpeval{-\ylength/2})%
	\color{gridcolor}%
	\edef\Scala{50}% The scale factor
%    \end{macrocode}
%
%
% Circle stroking. In linear scale 10 radial units are present,
% therefore, 10 circles are drawn with tick lines, 
% medium lines circles every 0.5 unit and thin lines circles every
% 0.1 unit.
%    \begin{macrocode}
	\fptest{#2=0}{% start circle linear radius sequence.
		\I=1
		\fpdowhile{\I=&lt;100}{\edef\R{\fpeval{0.01*\Scala*\I}}%
			{\fptest{\fpeval{\I-10(round(\I/10,0))}=0}{\linethickness{\lwa}%
				}%
				{\fptest{\fpeval{\I-5(round(\I/5,0))}=0}{\linethickness{\lwb}}%
					{\linethickness{\lwc}}%
				}\Circlewithcenter0,0radius\R
			}\advance\I by1\relax}%
	}% end circle linear radius sequence
	{%
	\edef\LnDieci{\fpeval{ln(10)}}%
    \edef\ScalaDecade{\fpeval{\Scala/#2}}%
	\fptest{#2&lt;3}{%
        \newcount\Dec \Dec=1\relax
		\fpdowhile{\Dec=&lt;#2}{%
            \linethickness{\lwa}%
            \edef\R{\fpeval{\Dec*\ScalaDecade}}%
            \Circlewithcenter0,0radius\R% Thick circles
			% First band from 1 to 4 (excluded)
			\edef\LPLA{1}%
			\fpdowhile{\LPLA&lt;4}{
				\edef\Logaritmo{\fpeval{\Dec-1+(ln(\LPLA))/\LnDieci}}%
				\edef\R{\fpeval{\ScalaDecade*\Logaritmo}}%
				\fptest{\R&gt;0}{\fptest{\LPLA=round(\LPLA,0)}%
					{\linethickness{\lwb}}{\linethickness{\lwc}}%
					\Circlewithcenter0,0radius\R}{}%
				\edef\LPLA{\fpeval{\LPLA+0.2}}}%
			% Second band from 4 to 10 included
			\edef\LPLA{4}%
			\fpdowhile{\LPLA=&lt;10}{%
				\edef\Logaritmo{\fpeval{\Dec-1+(ln(\LPLA))/\LnDieci}}%
				\edef\R{\fpeval{\ScalaDecade*\Logaritmo}}%
				\fptest{\R&gt;0}{\fptest{\LPLA=round(\LPLA,0)}%
					{\linethickness{\lwb}}{\linethickness{\lwc}}%
					\Circlewithcenter0,0radius\R}{}%
				\edef\LPLA{\fpeval{\LPLA+0.5}}}%
			\advance\Dec by1\relax}%
		}{%
			\ClassWarning{GraphPaper}{Logarithmic polar graph paper:\MessageBreak
				too many decades: \number#2\space\MessageBreak
				Reduce their number}%
		}}% End logarithmic circle radius sequence
	\ignorespaces
	%
%    \end{macrocode}
%
% Radial lines. \cs{I} represents the angle in degrees and it runs
% from 0 to 359. Tick lines every 10$^\circ$; medium lines every 5$^\circ$
% for units 2, 7, 8, 9, 10; thin lines every 2$^\circ$ for units 3, 4, 5, 6;
% thin lines every 1$^\circ$ for units 7, 8, 9, 10.
%    \begin{macrocode}
	\I=0\edef\R{\Scala}%
	\fpdowhile{\I&lt;360}{\edef\A{\fpeval{\I}}%
		\fptest{\fpeval{\I-10(round(\I/10,0))}=0}%
		{\linethickness{\lwa}\segment(0,0)(\A:\R)
			\Rbox[\A](\A:\R){\color{black}\A}}% multiple of 10
		{\fptest{\fpeval{\I-5(round(\I/5,0))}=0}%
			{\linethickness{\lwb}%
				\segment(\A:5)(\A:10)
				\segment(\A:30)(\A:\R)}% multiple of 5
			{\linethickness{\lwc}%
				\fptest{\fpeval{\I-2(round(\I/2,0))}=0}%
				{\segment(\A:10)(\A:\R)}% multiple of 2
				{\segment(\A:30)(\A:\R)}% multiple of 1
			}%
		}%
		\advance\I by 1\relax
	}\ignorespaces
%    \end{macrocode}
%
% Graduated axis.
%    \begin{macrocode}
    \GradPolar{#2}
%    \end{macrocode}
%
% Custom code provided by the user. After executing the code to compose
% the rectangular graph paper and the user custom code, the latter is
% reset if the \cs{GP@customcodereset} is true.
%    \begin{macrocode}
	\GP@custom
	\end{picture}
\ifGP@customcodereset\def\GP@custom{}\fi}
%    \end{macrocode}
%
%
%\subsubsection{Smith chart graph paper}
%
% The Smith chart graph paper is composed by the command \cs{SmithChart}:
%\begin{ttsyntax}
% \cs{SmithChart}\oarg{diameter}
%\end{ttsyntax}
% where
% \meta{diameter} is the dimension (plus some extra space for labels and
% margins)  of the Smith chart. Its default value corresponds to the
% \cs{paperheight} (the minimum dimension of the paper).
%
%    \begin{macrocode}
\NewDocumentCommand\SmithChart{O{\paperheight}}{%
    \newpage
    \parindent=0pt
    \pagestyle{empty}%
    \ifcsname pmargin\endcsname\relax\else\newlength\pmargin\fi
    \setlength{\pmargin}{20pt}
    \newgeometry{left=\pmargin,right=\pmargin,top=\pmargin,bottom=\pmargin}
    \def\factor{140}
    \unitlength=\fpeval{#1/\factor}pt\relax
    \def\xlength{\fpeval{(\textwidth-0.01pt)/\unitlength}} 
    \def\ylength{\fpeval{(\textheight-0.01pt)/\unitlength}}
    \begin{picture}(\xlength,\ylength)%
                   (\fpeval{-\xlength/2},\fpeval{-\ylength/2})%
	\color{gridcolor}%
	\edef\Scala{50}% scale factor based on the main circle but valid
	               % for everything inside the graph paper.
	{\color{black}\Pbox(0,0){}[4]}% Black dot in the origin
	% images of the vertical cartesian lines
	\I=0\relax
	\fpdowhile{\I=&lt;6}{\edef\Aux{\fpeval{\I/20}}{%
			\fptest{\I=0}{\color{black}}{\color{gridcolor}}\thicklines\Xcircle{\Aux}}%
		\advance\I by1\edef\Aux{\fpeval{\I/20}}\Xcircle{\Aux}%
		\advance\I by1\ignorespaces}%fino a 0.4
	\fpdowhile{\I=&lt;16}{\edef\Aux{\fpeval{\I/20}}\relax
		{\thicklines\Xcircle{\Aux}}\advance\I by2\edef\Aux{\fpeval{\I/20}}\relax
		\Xcircle{\Aux}\advance\I by2\ignorespaces}% fino a 1
	\fpdowhile{\I=&lt;36}{\edef\Aux{\fpeval{\I/20}}\relax
		{\thicklines\Xcircle{\Aux}}\advance\I by4\edef\Aux{\fpeval{\I/20}}\relax
		\Xcircle{\Aux}\advance\I by4\ignorespaces}% fino a 2
	\fpdowhile{\I=&lt;96}{\edef\Aux{\fpeval{\I/20}}\relax
		{\thicklines\Xcircle{\Aux}}\advance\I by8\edef\Aux{\fpeval{\I/20}}\relax
		\Xcircle{\Aux}\advance\I by8\ignorespaces}%fino a 5
	\fpdowhile{\I=&lt;296}{\edef\Aux{\fpeval{\I/20}}\relax
		{\thicklines\Xcircle{\Aux}}\advance\I by16\edef\Aux{\fpeval{\I/20}}\relax
		\Xcircle{\Aux}\advance\I by16\ignorespaces}% up to 15
% Images of the horizontal cartesian semi-lines
	\Ycircle{1}%
	{\thicklines\segment(-\Rzero,0)(\Rzero,0)}% diameter
	\Rbox[180](-\Rzero,0){0}\Rbox[0](\Rzero,0){\infty}
	\Ycircle{0.05}\Ycircle{-0.05}\I=2% \I=2 is to avoid a division by 0
	\fpdowhile{\I=&lt;18}{\edef\Aux{\fpeval{\I/20}}\relax
		{\thicklines\Ycircle{\Aux}*\Ycircle{-\Aux}*}%
		\advance\I by1\edef\Aux{\fpeval{\I/20}}\relax
		\Ycircle{\Aux}\Ycircle{-\Aux}\advance\I by 1\ignorespaces}% restarts from 1
	\fpdowhile{\I&lt;40}{\edef\Aux{\fpeval{\I/20}}\relax
		{\thicklines\Ycircle{\Aux}*\Ycircle{-\Aux}*}%
		\advance\I by 2\edef\Aux{\fpeval{\I/20}}\relax
		\Ycircle{\Aux}\Ycircle{-\Aux}\advance\I by 2\ignorespaces}% restarts from 2
	\fpdowhile{\I&lt;80}{\edef\Aux{\fpeval{\I/20}}\relax
		{\thicklines\Ycircle{\Aux}*\Ycircle{-\Aux}*}%
		\advance\I by 4\edef\Aux{\fpeval{\I/20}}\relax
		\Ycircle{\Aux}\Ycircle{-\Aux}\advance\I by 4\ignorespaces}% restarts from 4
	\fpdowhile{\I=&lt;140}{\edef\Aux{\fpeval{\I/20}}\relax
		{\thicklines\Ycircle{\Aux}*\Ycircle{-\Aux}*}%
		\advance\I by 10\edef\Aux{\fpeval{\I/20}}\relax
		\Ycircle{\Aux}\Ycircle{-\Aux}\advance\I by 10\ignorespaces}% stops at 7.5
	{\thicklines\Ycircle{8}*\Ycircle{-8}*}%
	% non linear graduation for the abscissas 
	\GradResist{62}%
	% Polar graduation in normalised wave length percentages 
	\edef\Rout{\fpeval{1.09*\Rzero}}%
	\edef\RoutCifre{\fpeval{\Rout+2}}%
	\edef\RoutTak{\fpeval{\Rout+1}}%
	{\color{black}%
		\Circlewithcenter 0,0radius\Rout
		\I=0\fpdowhile{\I&lt;10}%
		{\edef\LAng{\fpeval{180-\I*36}}\edef\Cifre{\fpeval{\I*5}}%
			\put(\LAng:\RoutCifre){%
				\rotatebox{\fpeval{\LAng-90}}{\makebox(0,0)[b]{\scriptsize\Cifre}}}%
			\advance\I by 1\ignorespaces}
		\I=0\fpdowhile{\I&lt;50}{%
			\edef\LAng{\fpeval{180-\I*7.2}}\segment(\LAng:\Rout)(\LAng:\RoutTak)%
			\advance\I by1\ignorespaces}
	%
	% Outside circle encloses everything except the abscissa graduation.
	% Everything lays inside a square 
		\Circlewithcenter0,0radius{\fpeval{\Scala+9}}}%
	% Now the user supplied code is executed
	\GP@custom
	\end{picture}
\ifGP@customcodereset\def\GP@custom{}\fi}%
%    \end{macrocode}
%
%
%\subsection{User interface}
%
% Here follows the user commands to draw the graph papers, as described in
% section~\ref{sec:howto}:
%    \begin{macrocode}
\NewDocumentCommand{\bilinear}{}{\carta{0}{0}}
\NewDocumentCommand{\semilogx}{m}{\carta{#1}{0}}
\NewDocumentCommand{\semilogy}{m}{\carta{0}{#1}}
\NewDocumentCommand{\loglog}{O{0}mm}{\carta[#1]{#2}{#3}}
\NewDocumentCommand{\polar}{}{\PolarChart{0}}
\NewDocumentCommand{\logpolar}{m}{\PolarChart{#1}}
\NewDocumentCommand{\smith}{}{\SmithChart}
%    \end{macrocode}
%
% The user commands to customise the appearance of the graph
% papers is defined. Their syntax was previously described in
% sectio~\ref{sec:howto}:
%    \begin{macrocode}
\NewDocumentCommand{\setgridcolor}{m}{\colorlet{gridcolor}{#1}}
\NewDocumentCommand{\setmajorlinethickness}{m}{\setlength{\lwa}{#1}}
\NewDocumentCommand{\setmediumlinethickness}{m}{\setlength{\lwb}{#1}}
\NewDocumentCommand{\setminorlinethickness}{m}{\setlength{\lwc}{#1}}
\NewDocumentCommand{\setminimumdistance}{m}{\setlength{\mindistanceunit}{#1}}
\NewDocumentCommand{\setxside}{m}{%
	\ifnum\fpeval{#1 &gt; \paperwidth}=1 \ClassError{graphpaper}{X side too wide!} \fi
	\setlength{\xsideunit}{#1}}
\NewDocumentCommand{\setyside}{m}{%
	\ifnum\fpeval{#1 &gt; \paperheight}=1 \ClassError{graphpaper}{Y side too wide!} \fi
	\setlength{\ysideunit}{#1}}
\def\GP@custom{}
\newif\ifGP@customcodereset \GP@customcoderesettrue
\NewDocumentCommand{\customcode}{O{1} m}{%
	\ifnum#1=\z@ \GP@customcoderesetfalse \fi%
	\def\GP@custom{#2}}
%    \end{macrocode}
%
%
%\subsection{Class code end}
%
%    \begin{macrocode}
%
\endinput
%    \end{macrocode}
%
%\iffalse
%&lt;/class&gt;
%\fi
%
% \Finale
%^^A</pre></body></html>