Help!! cant get this program to run

[izzy88]

this are the errors that i get:
1>c:\users\ismael\desktop\hw8\hw8\hw8.cpp(9) : error C2365: 'y1' : redefinition; previous definition was 'function'
1> c:\program files (x86)\microsoft visual studio 8\vc\include\math.h(460) : see declaration of 'y1'
1>c:\users\ismael\desktop\hw8\hw8\hw8.cpp(27) : error C2065: 't' : undeclared identifier
1>c:\users\ismael\desktop\hw8\hw8\hw8.cpp(28) : error C2659: '=' : function as left operand
1>c:\users\ismael\desktop\hw8\hw8\hw8.cpp(39) : error C2659: '=' : function as left operand
1>c:\users\ismael\desktop\hw8\hw8\hw8.cpp(48) : error C2659: '=' : function as left operand
1>c:\users\ismael\desktop\hw8\hw8\hw8.cpp(57) : error C2659: '=' : function as left operand
*********************************************************
#include <stdlib.h>
#include <stdio.h>
#include <math.h>


//globals
double y1,y2,y3,dt,k1,k2,k3,k4,L1,L2,L3,L4,m1,m2,m3,m4,y1old,y2old,y3old,told,y1new,y2new,y3new,tnew,ans1,ans2,ans3;
int i;
//FPS
double eqn1(double y2, double t);
double eqn2 ( double y3);
double eqn3 ( double y1, double y2, double t );

void main ()
{
//input by replacement
told=1.0;
y1old=0.0;
y2old=1.0;
y3old=2.0;
dt=0.1;
//LOOP
for (i=0;i<=9;i=i+1)
{
//update 1
t = told;
y1 = y1old;
y2 = y2old;
y3 = y3old;
//get K1,L1,m1

k1 = eqn1 (y2,t)*dt;
L1 = eqn2 (y3)*dt;
m1 = eqn3 (y1,y2,t)*dt;

//update #2
t = told + dt/2.0;
y1 = (y1old + k1/2.0);
y2 = (y2old + L1/2.0);
y3 = (y3old + m1/2.0);
// get k2,L2,m2
k2 = eqn1 (y2,t) *dt;
L2 = eqn2 (y3) *dt;
m2 = eqn3 (y1,y2,t)*dt;
//update #3
t= told +dt/2.0;
y1=y1old + k2/2.0;
y2= y2old + L2/2.0;
y3= y3old + m2/2.0;
// get k3,L3,m3
k3= eqn1 (y2,t)*dt;
L3= eqn2(y3)*dt;
m3= eqn3(y1,y2,t)*dt;
//update#4
t= told+ dt;
y1= y1old+ k3;
y2= y2old + L3;
y3= y3old +m3;
// get k4,L4,m4
k4= eqn1(y2,t)*dt;
L4= eqn2 ( y3)*dt;
m4= eqn3(y1,y2,t)*dt;

y1new= y1old + (1.0/6.0)*(k1+ 2.0*k2 + 2.0*k3 + k4);
y2new= y2old + (1.0/6.0)*(L1+ 2.0*L2 + 2.0*L3 + L4);
y3new= y3old + (1.0/6.0)*(m1+ 2.0*m2 + 2.0*m3 + m4);
tnew= told + dt;
y1old= y1new;
y2old= y2new;
y3old= y3new;
told= tnew;
//close loop

}
// end main
return;
}

// These subs go after closing main


double eqn1( double y2, double t)
{
ans1 = y2-t;
return(ans1);
}

double eqn2 (double y3)
{
ans2=y3;
return(ans2);
}
double eqn3 ( double y1, double y2, double t)
{
ans3=6.0* y2-12.0*y1*t*t;
return(ans3);
}

[b2ee]

y1(x) is a math function in math.h already which may you don't realize that. Change your global "y1" to any other name.

"y1(x) Bessel function of x of the second kind of order 1" in math.h

By the way, please use "code" past function to copy your code into the forum.