function [x,y]=piecewise(f,g,a,b,c,n)
% Usage: [y,x]=piecewise(f,g,a,b,c,n)
%
% this m-function generates n+1 nodes between x=a 
% and x=b.  It then generates n+1 function evaluations 
% for a piecewise defined function using f(x) for 
% a <= x <= c and g(x) for c <= x <= b.
%
% input:
% f  - a predefined m-file called 'f1'
% g  - a predefined m-file called 'f2'
% a  - initial value of x
% b  - terminal value of x
% c  - some value between a and b where 
%        the function changes rules 
% n  - the number of equal subintervals between a and b
%
% output:
% x  - an array of n+1 equally spaced nodes 
%         between a and b
% y  - an array of n+1 function values
%
delx=(b-a)/n;
x=a:delx:b;
y=zeros(1,n+1);
z=feval(f,x(1,1));
for i=1:n+1
    if x(1,i)<c
        y(1,i)=feval(f,x(1,i));
    else
        y(1,i)=feval(g,x(1,i));
    end
end
plot(x,y)
endfunction

function f = f(x)
  f=(x-2)^2;
endfunction

function g = g(x)
  g=3*(x-2);
endfunction

title("piecewise function");
xlabel("x");
ylabel("function values");
piecewise("f","g",1,3,2,100);