function dY=odvod(X,par)
%odvod sistema enacb za veriznico (glej 'sistem.m' / derivative of the
%function in 'sistem.m'
a=X(1);%neznanki / unknowns
b=X(2);
H=par(1);%visinska razlika / hight difference
L=par(2);%dolzina vrvi / length of wire
D=par(3);%razpon / distance to be bridged
dY=[
    cosh(b/a)-cosh((b-D)/a)+1/a*(-b*sinh(b/a)+(b-D)*sinh((b-D)/a)),sinh(b/a)-sinh((b-D)/a);
    sinh(b/a)-sinh((b-D)/a)+1/a*(-b*cosh(b/a)+(b-D)*cosh((b-D)/a)),cosh(b/a)-cosh((b-D)/a)
    ];
end