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Problem (Access violation (Segmentation Fault))

Apr 15, 2010 at 5:21pm
maysmech (6)
Hello
My Code leads to Error: Access violation (Segmentation Fault)
it is a heat transfer problem which calculate temperature of a canal.
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#include <iostream>
#include <cmath>
#include<cstdio>
using namespace std;

#define I 15
#define J 18

int main ()
{
	int i, j, ts;
	double T[I][J][2], delt=.001, L=1, delx=L*I/15/6;
	double K=3,cp=400.0, p=2150.0, alpha=K/(p*cp), T1=80, T2=20;
	double Fo=alpha*delt/delx/delx, h1=5, h2=100, Bi1=h1*delx/K, Bi2=h2*delx/K;
	FILE *fd;
	fd=fopen("cfd1.plt","w");
	if((fd=fopen("cfd1.plt","w"))==NULL)
	{
		cout<<"cannot open file"<<endl;
	}
	for(i=0;i<=15;i++)                          //Initial Value Definition
	{
		for(j=0;j<=(18/9);j++)
		{
			T[i][j][0]=20;
		} 
		for(j=(7*J/9);j<=(J);j++)
		{
			T[i][j][0]=20;
		}
	}	
	

	for(j=(J/9);j<=(7*J/9);j++)
	{
		for(i=0;i<=(2*I/15);i++)
		{
			T[i][j][0]=20;
		}
		for(i=(14*I/15);i<=(I);i++)
		{
			T[i][j][0]=20;
		}
	}
	
	for(ts=0;ts<1;ts++)                     //Solve for Different Times
	{	
		for(i=1;i<I;i++)
		{	
			for(j=1;j<(J/9);j++)
			{
				T[i][j][1]=T[i][j][0]+Fo*(T[i+1][j][0]-2*T[i][j][0]+T[i-1][j][0])+Fo*(T[i][j+1][0]-2*T[i][j][0]+T[i][j-1][0]);
			}
			for(j=(7*J/9+1);j<J;j++)
			{
				T[i][j][1]=T[i][j][0]+Fo*(T[i+1][j][0]-2*T[i][j][0]+T[i-1][j][0])+Fo*(T[i][j+1][0]-2*T[i][j][0]+T[i][j-1][0]);
			}
		}
		for(j=(J/9+1);j<(7*J/9);j++)
		{	
			for(i=1;(i<2*I/15);i++)
			{
				T[i][j][1]=T[i][j][0]+Fo*(T[i+1][j][0]-2*T[i][j][0]+T[i-1][j][0])+Fo*(T[i][j+1][0]-2*T[i][j][0]+T[i][j-1][0]);
			}
			for(i=14*I/15;(i<I);i++)
			{
				T[i][j][1]=T[i][j][0]+Fo*(T[i+1][j][0]-2*T[i][j][0]+T[i-1][j][0])+Fo*(T[i][j+1][0]-2*T[i][j][0]+T[i][j-1][0]);
			}
		}	

		
		for(i=1;i<2*I/15;i++)                   //Boundarie Between 4 Blocks
		{
			T[i][J/9][1]=T[i][J/9][0]+Fo*(T[i+1][J/9][0]-2*T[i][J/9][0]+T[i-1][J/9][0])+Fo*(T[i][J/9+1][0]-2*T[i][J/9][0]+T[i][J/9-1][0]);			
		}
		for(i=14*I/15+1;i<I;i++)
		{
			T[i][J/9][1]=T[i][J/9][0]+Fo*(T[i+1][J/9][0]-2*T[i][J/9][0]+T[i-1][J/9][0])+Fo*(T[i][J/9+1][0]-2*T[i][J/9][0]+T[i][J/9-1][0]);			
		}
		for(i=1;i<2*I/15;i++)
		{
			T[i][7*J/9][1]=T[i][7*J/9][0]+Fo*(T[i+1][7*J/9][0]-2*T[i][7*J/9][0]+T[i-1][7*J/9][0])+Fo*(T[i][7*J/9+1][0]-2*T[i][7*J/9][0]+T[i][7*J/9-1][0]);			
		}
		for(i=14*I/15+1;i<I;i++)
		{
			T[i][7*J/9][1]=T[i][7*J/9][0]+Fo*(T[i+1][7*J/9][0]-2*T[i][7*J/9][0]+T[i-1][7*J/9][0])+Fo*(T[i][7*J/9+1][0]-2*T[i][7*J/9][0]+T[i][7*J/9-1][0]);			
		}
		                                        //8 Internals & Externals Points
		T[2*I/15][J/9][1]=2/3*Fo*(T[2*I/15+1][J/9][0]+2*T[2*I/15-1][J/9][0]+2*T[2*I/15][J/9-1][0]+T[2*I/15][J/9+1][0]+2*Bi1*T1)+(1-4*Fo-4/3*Bi1*Fo)*T[2*I/15][J/9][0];
		T[14*I/15][J/9][1]=2/3*Fo*(T[14*I/15-1][J/9][0]+2*T[14*I/15+1][J/9][0]+2*T[14*I/15][J/9-1][0]+T[14*I/15][J/9+1][0]+2*Bi1*T1)+(1-4*Fo-4/3*Bi1*Fo)*T[14*I/15][J/9][0];
		T[2*I/15][7*J/9][1]=2/3*Fo*(T[2*I/15+1][7*J/9][0]+2*T[2*I/15-1][7*J/9][0]+2*T[2*I/15][7*J/9+1][0]+T[2*I/15][7*J/9-1][0]+2*Bi1*T1)+(1-4*Fo-4/3*Bi1*Fo)*T[2*I/15][7*J/9][0];
		T[14*I/15][7*J/9][1]=2/3*Fo*(T[14*I/15-1][7*J/9][0]+2*T[14*I/15+1][7*J/9][0]+2*T[14*I/15][7*J/9+1][0]+T[14*I/15][7*J/9-1][0]+2*Bi1*T1)+(1-4*Fo-4/3*Bi1*Fo)*T[14*I/15][7*J/9][0];

		T[I][J][1]=2*Fo*(T[I-1][J][0]+T[I][J-1][0]+2*Bi2*T2)+(1-4*Fo-4*Bi2*Fo)*T[I][J][0];		
		T[I][0][1]=2*Fo*(T[I-1][0][0]+T[I][1][0]+2*Bi2*T2)+(1-4*Fo-4*Bi2*Fo)*T[I][0][0];
		T[0][J][1]=2*Fo*(T[1][J][0]+T[0][J-1][0]+2*Bi2*T2)+(1-4*Fo-4*Bi2*Fo)*T[0][J][0];		
		T[0][0][1]=2*Fo*(T[1][0][0]+T[0][1][0]+2*Bi2*T2)+(1-4*Fo-4*Bi2*Fo)*T[0][0][0];		
		
		for(i=2*I/15+1;i<14*I/15;i++)           //2 Internal Horizontal Boundaries
		{
			T[i][J/9][1]=Fo*(2*T[i][J/9-1][0]+T[i-1][J/9][0]+T[i+1][J/9][0]+2*Bi1*T1)+(1-4*Fo-4*Bi1*Fo)*T[i][J/9][0];
			T[i][7*J/9][1]=Fo*(2*T[i][7*J/9+1][0]+T[i-1][7*J/9][0]+T[i+1][7*J/9][0]+2*Bi1*T1)+(1-4*Fo-4*Bi1*Fo)*T[i][7*J/9][0];
		}
		for(i=1;i<I;i++)                       //2 External Horizontal Boundaries
		{
			T[i][0][1]=Fo*(2*T[i][1][0]+T[i-1][0][0]+T[i+1][0][0]+2*Bi2*T2)+(1-4*Fo-4*Bi2*Fo)*T[i][0][0];
			T[i][J][1]=Fo*(2*T[i][J-1][0]+T[i+1][J][0]+T[i-1][J][0]+2*Bi2*T2)+(1-4*Fo-4*Bi2*Fo)*T[i][J][0];
		}
		for(j=J/9+1;j<7*J/9;j++)               //2 Internal Vertical Boundaries
		{
			T[2*I/15][j][1]=Fo*(2*T[2*I/15-1][j][0]+T[2*I/15][j+1][0]+T[2*I/15][j-1][0]+2*Bi1*T1)+(1-4*Fo-4*Bi1*Fo)*T[2*I/15][j][0];
			T[14*I/15][j][1]=Fo*(2*T[14*I/15+1][j][0]+T[14*I/15][j+1][0]+T[14*I/15][j-1][0]+2*Bi1*T1)+(1-4*Fo-4*Bi1*Fo)*T[14*I/15][j][0];
		}
		for(j=0;j<J;j++)                      //2 External Vertical Boundaries
		{
			T[0][j][1]=Fo*(2*T[1][j][0]+T[0][j+1][0]+T[0][j-1][0]+2*Bi2*T2)+(1-4*Fo-4*Bi2*Fo)*T[0][j][0];
			T[I][j][1]=Fo*(2*T[I-1][j][0]+T[I][j+1][0]+T[I][j-1][0]+2*Bi2*T2)+(1-4*Fo-4*Bi2*Fo)*T[I][j][0];
		}
	for(i=0;i<=I;i++)
		for(j=0;j<=J;j++)
		{
		T[i][j][0]=T[i][j][1];
		}
		
	}
	
	
	for(i=0;i<=I;i++)
	{
		for(j=0;j<=J;j++)
		{
			fprintf(fd,"%d\t%d\t%.12f\n",i,j,T[i][j][0]);
		}
	}
	fclose(fd);
	
return 0;
}
Edit & run on cpp.sh
Apr 15, 2010 at 5:26pm
closed account (S6k9GNh0)
holy crap
Apr 15, 2010 at 5:27pm
helios (17607)
Segmentation Fault
T[2*I/15][J/9][1]=2/3*Fo*(T[2*I/15+1][J/9][0]+2*T[2*I/15-1][J/9][0]+2*T[2*I/15][J/9-1][0]+T[2*I/15][J/9+1][0]+2*Bi1*T1)+(1-4*Fo-4/3*Bi1*Fo)*T[2*I/15][J/9][0];
Big surprise, there.

You're opening the same file twice, by the way.
Apr 15, 2010 at 5:44pm
maysmech (6)
it is not file. it is 3-D array which its 3rd dimension is time and 1 is newer and 0 is older temperature
Apr 15, 2010 at 5:46pm
oghmaosiris (157)
I think s/he's referring to:

fd=fopen("cfd1.plt","w");
if((fd=fopen("cfd1.plt","w"))==NULL)
Apr 15, 2010 at 6:00pm
maysmech (6)
No, i deactivate those but no change occured.
Apr 15, 2010 at 7:35pm
maysmech (6)
what should i do?
Apr 15, 2010 at 7:42pm
Albatross (4553)
Segmentation fault: Occurs when the program tries to access or modify inexistent/unreachable data pointed to by a pointer of sorts. To fix that problem, find the pointer.

Heh, good luck with that...

-Albie
Apr 15, 2010 at 8:35pm
oghmaosiris (157)
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for(i=0;i<=15;i++)                          //Initial Value Definition
	{
		for(j=0;j<=(18/9);j++)
		{
			T[i][j][0]=20;
		} 
		for(j=(7*J/9);j<=(J);j++)
		{
			T[i][j][0]=20;
		}
	}	
	

	for(j=(J/9);j<=(7*J/9);j++)
	{
		for(i=0;i<=(2*I/15);i++)
		{
			T[i][j][0]=20;
		}
		for(i=(14*I/15);i<=(I);i++)
		{
			T[i][j][0]=20;
		}


I think it might be with these for loops.
Apr 16, 2010 at 6:24am
maysmech (6)
no, it is defining of matrix and no loop is seen.
Apr 16, 2010 at 8:28am
maysmech (6)
???
Apr 16, 2010 at 4:30pm
closed account (S6k9GNh0)
Not going to lie. Why don't you use a debugger so you can find the exact line it crashes on.
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