<?xml version="1.0" encoding="UTF-8"?>
<!--
 * Scilab ( https://www.scilab.org/ ) - This file is part of Scilab
 * Copyright (C) ENPC - Jean-Philippe Chancelier
 *
 * Copyright (C) 2012 - 2016 - Scilab Enterprises
 *
 * This file is hereby licensed under the terms of the GNU GPL v2.0,
 * pursuant to article 5.3.4 of the CeCILL v.2.1.
 * This file was originally licensed under the terms of the CeCILL v2.1,
 * and continues to be available under such terms.
 * For more information, see the COPYING file which you should have received
 * along with this program.
 *
 -->
<refentry xmlns="http://docbook.org/ns/docbook" xmlns:xlink="http://www.w3.org/1999/xlink" xmlns:svg="http://www.w3.org/2000/svg" xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:db="http://docbook.org/ns/docbook" xmlns:scilab="http://www.scilab.org"  xml:lang="en" xml:id="xchange">
    <refnamediv>
        <refname>xchange</refname>
        <refpurpose>transform real to pixel coordinates</refpurpose>
    </refnamediv>
    <refsynopsisdiv>
        <title>Syntax</title>
        <synopsis>[x1, y1, rect] = xchange(x, y, dir)</synopsis>
    </refsynopsisdiv>
    <refsection>
        <title>Arguments</title>
        <variablelist>
            <varlistentry>
                <term>x, y</term>
                <listitem>
                    <para>
                        two matrices of size <literal>(n1, n2)</literal>
                        (coordinates of a set of points).
                    </para>
                </listitem>
            </varlistentry>
            <varlistentry>
                <term>dir</term>
                <listitem>
                    <para>
                        a string, parameter used to specify the conversion type
                        (See "Description" for details).
                    </para>
                </listitem>
            </varlistentry>
            <varlistentry>
                <term>x1, y1</term>
                <listitem>
                    <para>
                        two matrices of size <literal>(n1, n2)</literal>
                        (coordinates of the set of points).
                    </para>
                </listitem>
            </varlistentry>
            <varlistentry>
                <term>rect</term>
                <listitem>
                    <para>a vector of size 4.</para>
                </listitem>
            </varlistentry>
        </variablelist>
    </refsection>
    <refsection>
        <title>Description</title>
        <para>
            After having used a graphics function, <function>xchange</function>
            computes pixel coordinates from real coordinates and conversely,
            according to the value of the parameter <varname>dir</varname>:
            <literal>"f2i"</literal> (float to int) means real to pixel and
            <literal>"i2f"</literal> (int to float) means pixel to real.
        </para>
        <para>
            <varname>x1</varname> and <varname>y1</varname> are the new
            coordinates of the set of points defined by the old coordinates
            <varname>x</varname> and <varname>y</varname>.
        </para>
        <para>
            <varname>rect</varname> is the coordinates in pixel of the rectangle
            in which the plot was done: <literal>[upper-left point, width, height]</literal>.
        </para>
    </refsection>
    <refsection>
        <title>Examples</title>
        <programlisting role="example"><![CDATA[
t=[0:0.1:2*%pi]';
plot2d(t,sin(t))
[x,y,rect]=xchange(1,1,"f2i")
[x,y,rect]=xchange(0,0,"i2f")
 ]]></programlisting>
    </refsection>
</refentry>
