function y=volterra(g,k,x)
% - Solving the Volterra integral equation by laplace transform
% -          y=g(x)+integral(K(x-t)*y(t),t,0:x)=g(x)+(K convolution y)=g(x)+K@y
% -
% - Let       F= laplace(sym('y'))
% -      then    laplace(k@y)= laplace(k) times F
% -   phi1=laplace(g)
% -   phi2=laplace(k)
% -   F=   phi1/(1-phi2)
% - 
% - so   y=inverse laplace transform of F
% -  return  y=ilaplace(Y)
% -  usage syms x define  x g k  y=volterra(g,k,x)
% -  example  
% -         syms x g k 
% -           g=1+x;   k=exp(x); y=volterra(g,k,x);
% - note in some cases when g=constant=say(5)  you should write it g=5+0*x 
% - see also the last option on examples on laplace and volterra.
% -
syms x s phi1 phi2 
disp(' you are solving   y=g+ K o y ')
disp(' by laplace transform  F= L(g)/(1-L(k))')
disp(' the solution y is ilaplace(F)')
disp(' where g(x)= ');disp(g)
disp( ' and   k(x)= ');disp(k)

phi1=laplace(g);
disp('phi1=laplace(g)=')
phi1=simplify(phi1)
phi2=laplace(k);
disp('phi2=laplace(k)=')
phi2=simplify(phi2)
F=simplify(phi1/(1-phi2));
F=factor(F)
y=ilaplace(F);
t=x;
y=subs(y);
return