<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN"> <HTML ><HEAD ><TITLE >gmp_gcdext</TITLE ><META NAME="GENERATOR" CONTENT="Modular DocBook HTML Stylesheet Version 1.7"><LINK REL="HOME" TITLE="Manual PHP" HREF="index.html"><LINK REL="UP" TITLE="GMP Functions" HREF="ref.gmp.html"><LINK REL="PREVIOUS" TITLE="gmp_gcd" HREF="function.gmp-gcd.html"><LINK REL="NEXT" TITLE="gmp_hamdist" HREF="function.gmp-hamdist.html"><META HTTP-EQUIV="Content-type" CONTENT="text/html; charset=ISO-8859-2"></HEAD ><BODY CLASS="refentry" BGCOLOR="#FFFFFF" TEXT="#000000" LINK="#0000FF" VLINK="#840084" ALINK="#0000FF" ><DIV CLASS="NAVHEADER" ><TABLE SUMMARY="Header navigation table" WIDTH="100%" BORDER="0" CELLPADDING="0" CELLSPACING="0" ><TR ><TH COLSPAN="3" ALIGN="center" >Manual PHP</TH ></TR ><TR ><TD WIDTH="10%" ALIGN="left" VALIGN="bottom" ><A HREF="function.gmp-gcd.html" ACCESSKEY="P" >Înapoi</A ></TD ><TD WIDTH="80%" ALIGN="center" VALIGN="bottom" ></TD ><TD WIDTH="10%" ALIGN="right" VALIGN="bottom" ><A HREF="function.gmp-hamdist.html" ACCESSKEY="N" >Înainte</A ></TD ></TR ></TABLE ><HR ALIGN="LEFT" WIDTH="100%"></DIV ><H1 ><A NAME="function.gmp-gcdext" ></A >gmp_gcdext</H1 ><DIV CLASS="refnamediv" ><A NAME="AEN33206" ></A ><P > (PHP 4 >= 4.0.4, PHP 5)</P >gmp_gcdext -- Calculate GCD and multipliers</DIV ><DIV CLASS="refsect1" ><A NAME="AEN33209" ></A ><H2 >Description</H2 >array <B CLASS="methodname" >gmp_gcdext</B > ( resource a, resource b)<BR ></BR ><P > Calculates g, s, and t, such that <VAR CLASS="literal" >a*s + b*t = g = gcd(a,b)</VAR >, where gcd is the greatest common divisor. Returns an array with respective elements g, s and t. </P ><P > This function can be used to solve linear Diophantine equations in two variables. These are equations that allow only integer solutions and have the form: <VAR CLASS="literal" >a*x + b*y = c</VAR >. For more information, go to the <A HREF="http://mathworld.wolfram.com/DiophantineEquation.html" TARGET="_top" >"Diophantine Equation" page at MathWorld</A > </P ><P > <TABLE WIDTH="100%" BORDER="0" CELLPADDING="0" CELLSPACING="0" CLASS="EXAMPLE" ><TR ><TD ><DIV CLASS="example" ><A NAME="AEN33226" ></A ><P ><B >Exemplu 1. Solving a linear Diophantine equation</B ></P ><TABLE BORDER="0" BGCOLOR="#E0E0E0" CELLPADDING="5" ><TR ><TD ><code><font color="#000000"> <font color="#0000BB"><?php<br /></font><font color="#FF8000">// Solve the equation a*s + b*t = g<br />// where a = 12, b = 21, g = gcd(12, 21) = 3<br /></font><font color="#0000BB">$a </font><font color="#007700">= </font><font color="#0000BB">gmp_init</font><font color="#007700">(</font><font color="#0000BB">12</font><font color="#007700">);<br /></font><font color="#0000BB">$b </font><font color="#007700">= </font><font color="#0000BB">gmp_init</font><font color="#007700">(</font><font color="#0000BB">21</font><font color="#007700">);<br /></font><font color="#0000BB">$g </font><font color="#007700">= </font><font color="#0000BB">gmp_gcd</font><font color="#007700">(</font><font color="#0000BB">$a</font><font color="#007700">, </font><font color="#0000BB">$b</font><font color="#007700">);<br /></font><font color="#0000BB">$r </font><font color="#007700">= </font><font color="#0000BB">gmp_gcdext</font><font color="#007700">(</font><font color="#0000BB">$a</font><font color="#007700">, </font><font color="#0000BB">$b</font><font color="#007700">);<br /><br /></font><font color="#0000BB">$check_gcd </font><font color="#007700">= (</font><font color="#0000BB">gmp_strval</font><font color="#007700">(</font><font color="#0000BB">$g</font><font color="#007700">) == </font><font color="#0000BB">gmp_strval</font><font color="#007700">(</font><font color="#0000BB">$r</font><font color="#007700">[</font><font color="#DD0000">'g'</font><font color="#007700">]));<br /></font><font color="#0000BB">$eq_res </font><font color="#007700">= </font><font color="#0000BB">gmp_add</font><font color="#007700">(</font><font color="#0000BB">gmp_mul</font><font color="#007700">(</font><font color="#0000BB">$a</font><font color="#007700">, </font><font color="#0000BB">$r</font><font color="#007700">[</font><font color="#DD0000">'s'</font><font color="#007700">]), </font><font color="#0000BB">gmp_mul</font><font color="#007700">(</font><font color="#0000BB">$b</font><font color="#007700">, </font><font color="#0000BB">$r</font><font color="#007700">[</font><font color="#DD0000">'t'</font><font color="#007700">]));<br /></font><font color="#0000BB">$check_res </font><font color="#007700">= (</font><font color="#0000BB">gmp_strval</font><font color="#007700">(</font><font color="#0000BB">$g</font><font color="#007700">) == </font><font color="#0000BB">gmp_strval</font><font color="#007700">(</font><font color="#0000BB">$eq_res</font><font color="#007700">));<br /><br />if (</font><font color="#0000BB">$check_gcd </font><font color="#007700">&& </font><font color="#0000BB">$check_res</font><font color="#007700">) {<br /> </font><font color="#0000BB">$fmt </font><font color="#007700">= </font><font color="#DD0000">"Solution: %d*%d + %d*%d = %d\n"</font><font color="#007700">;<br /> </font><font color="#0000BB">printf</font><font color="#007700">(</font><font color="#0000BB">$fmt</font><font color="#007700">, </font><font color="#0000BB">gmp_strval</font><font color="#007700">(</font><font color="#0000BB">$a</font><font color="#007700">), </font><font color="#0000BB">gmp_strval</font><font color="#007700">(</font><font color="#0000BB">$r</font><font color="#007700">[</font><font color="#DD0000">'s'</font><font color="#007700">]), </font><font color="#0000BB">gmp_strval</font><font color="#007700">(</font><font color="#0000BB">$b</font><font color="#007700">),<br /> </font><font color="#0000BB">gmp_strval</font><font color="#007700">(</font><font color="#0000BB">$r</font><font color="#007700">[</font><font color="#DD0000">'t'</font><font color="#007700">]), </font><font color="#0000BB">gmp_strval</font><font color="#007700">(</font><font color="#0000BB">$r</font><font color="#007700">[</font><font color="#DD0000">'g'</font><font color="#007700">]));<br />} else {<br /> echo </font><font color="#DD0000">"Error while solving the equation\n"</font><font color="#007700">;<br />}<br /> <br /></font><font color="#FF8000">// output: Solution: 12*2 + 21*-1 = 3<br /></font><font color="#0000BB">?></font> </font> </code></TD ></TR ></TABLE ></DIV ></TD ></TR ></TABLE > </P ></DIV ><DIV CLASS="NAVFOOTER" ><HR ALIGN="LEFT" WIDTH="100%"><TABLE SUMMARY="Footer navigation table" WIDTH="100%" BORDER="0" CELLPADDING="0" CELLSPACING="0" ><TR ><TD WIDTH="33%" ALIGN="left" VALIGN="top" ><A HREF="function.gmp-gcd.html" ACCESSKEY="P" >Înapoi</A ></TD ><TD WIDTH="34%" ALIGN="center" VALIGN="top" ><A HREF="index.html" ACCESSKEY="H" >Acasã</A ></TD ><TD WIDTH="33%" ALIGN="right" VALIGN="top" ><A HREF="function.gmp-hamdist.html" ACCESSKEY="N" >Înainte</A ></TD ></TR ><TR ><TD WIDTH="33%" ALIGN="left" VALIGN="top" >gmp_gcd</TD ><TD WIDTH="34%" ALIGN="center" VALIGN="top" ><A HREF="ref.gmp.html" ACCESSKEY="U" >Sus</A ></TD ><TD WIDTH="33%" ALIGN="right" VALIGN="top" >gmp_hamdist</TD ></TR ></TABLE ></DIV ></BODY ></HTML >