What am I doing wrong?

[Scrat]

Okay, so I haven't touched c++ in a while (I wasn't that good to begin with either)...my program is as follows:

#include<iostream>
#include<cmath>
#include<iomanip>
using namespace std;

int main()
{
        double q,w;//boundary conditions
        q =0.0;
        w =8.0;
        double a[7];//array where values are stored
        int u = 0;
        cout<<setprecision(2)<<setiosflags(ios::fixed)<<q<<" ";
        double x = 1.0;
        for(int f = 0; f < 7; f++)
        {
                double e = 1.0/8.0;
                double g;
                double v;
                double c;
                g = x*e;
                v = 16-x;
                c = g*v;
                a[u] = c;//finds initial conditions
                u++;
                x++;
                cout<<setprecision(2)<<setiosflags(ios::fixed)<<c<<"  ";
        }
        cout<<setprecision(2)<<setiosflags(ios::fixed)<<w<<endl;

        for(int i = 0; i < 20; i++)//20 lines of steps
        {
                cout<<setprecision(2)<<setiosflags(ios::fixed)<<q<<" ";
                int z = 0;
                for(int t = 0; t<7; t++)
                {
                double l;
                int y = 0;
                int p = 1;
                int m = 2;
                if(z == 0)//for initial corner of delta x
                {
                        l = (a[0]/2.0)+(a[1]/4.0);
                        cout<<setprecision(2)<<setiosflags(ios::fixed)<<l<<"  ";
                        z++;
                }
                else if(z < 6)//for middle terms of delta x
                {
                        double j;
                        j = (a[y]/4.0)+(a[p]/2.0)+(a[m]/4.0);
                        cout<<setprecision(2)<<setiosflags(ios::fixed)<<j<<"  ";
                
                        a[p] = j;
                        z++;
                        y++;//moves to the next numbers in the array
                        p++;
                        m++;
                }
                else if(z == 6)//for ending points of delta x
                {
                        double b;
                        b = (a[5]/4.0)+(a[6]/2.0)+(w/4.0);
                        cout<<setprecision(2)<<setiosflags(ios::fixed)<<b<<"  ";
                        a[6] = b;
                        z++;
                        
                }
        a[0] =l;//to get the first changed number
        }
        cout<<setprecision(2)<<setiosflags(ios::fixed)<<w<<endl;
        }
return 0;
}

This is an assignment of mine...the instructions were to write a program to solve the heat equation. Boundary conditions are 0 <= t <= 5, 0 <= x <= 8, and u(0,t)=0, u(8,t) = 8, s = 1/4

Initial condition is u(x,0) = (1/8)*x*(16-x)

The program should print out 20 t-steps, or lines, with accuracy to 2 decimals. At this point my program isn't even printing anything out, so I don't even know if the program itself is messed up or not.

Any help is greatly appreciated.

[Amahdy]

I think you just need a "pause" before the dos-console gone away...
before "return 0;" put anything that hold the black screen for some time ...
maybe system("PAUSE"); >>>u need include<windows.h>
or maybe a getch(); >>> u need include<conio.h>
or just use any of your variables:
cin>>q;

hope this can helps.

[Hack]

Welcome to DevX :WAVE:

I edited your post and added [code]your code goes here[/code] tags to what you posted. As you can see, using the tags make it much easier to read and follow.

Thanks and once again, welcome aboard. :)