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// Scilab ( http://www.scilab.org/ ) - This file is part of Scilab
// Copyright (C) ????-2008 - INRIA
//
// This file must be used under the terms of the CeCILL.
// This source file is licensed as described in the file COPYING, which
// you should have received as part of this distribution. The terms
// are also available at
// http://www.cecill.info/licences/Licence_CeCILL_V2.1-en.txt
function [p] = derivat(p)
//pd=derivat(p) computes the derivative of the polynomial or rational
//function marix relative to the dummy variable
//
select typeof(p)
case "constant" then
p = 0*p; // includes case p == []
case "polynomial" then
var = varn(p); // dummy variable
[m,n]=size(p);
deg = degree(p);
degmax = max(deg);
if (degmax < n*m)
x = poly(0, var);
pd = zeros(p) * x;
for i = 1:degmax
pd = pd + coeff(p,i) * i * x^(i-1);
end
p = pd;
else
for i=1:m
for j=1:n
pij=p(i,j);
nij=deg(i,j);
if (nij==0) then
p(i,j)=0;
else
pij=coeff(pij).*(0:nij);
p(i,j)=poly(pij(2:nij+1),var,"c");
end
end
end
end
case "rational" then
num = p.num;
den = p.den;
num = derivat(num) .* den - num .* derivat(den);
den = den.^2;
p.num = num;
p.den = den;
else
error(msprintf(gettext("%s: Wrong type for input argument #%d: A floating point number or polynomial or rational fraction array expected.\n"),"derivat",1))
end
endfunction
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