segmentation fault when calling a function

Segmentation fault when calling the Update_Multiplier and gdb debugger shows these:

Program received signal SIGSEGV, Segmentation fault. 0x080b74e8 in Update_Multiplier() ()

double upperbound = 116325;
double objective = 1.1707e+07;
int main()
{
    Update_Multiplier();
}
void Update_Multiplier()
{
    cout << "function 0" << endl;
    // Determine subgradient vectors
    double gra[1000][1000];
    double grb[1000][1000];
    double dumX = 0;
    double stepsize[1000][1000];
    double tuning=2;
    double LRADum[1000][1000];
    double LRBDum[1000][1000];

    cout << "function 1" << endl;
    // update subgradient vectors
    for (int i=1; i<=noOfNodes; i++)
    {
        for (int j=1; j<=noOfNodes; j++)
        {
            if (C[i][j] != 0)
            {
                dumX=0;
                for (int p=1; p<=noOfCommodity; p++)
                {
                    dumX += X[i][j][p];
                }
                gra[i][j]=dumX-U[i][j]*Y[i][j]-Q[i][j];
                grb[i][j]=Q[i][j]-B[i][j]*Y[i][j];
            }
        }
    }

    // update stepsize
    cout << "function 2" << endl;
    for (int i=1; i<=noOfNodes; i++)
    {
        for (int j=1; j<=noOfNodes; j++)
        {
            if (C[i][j] != 0)
 开发者_开发问答           {
                stepsize[i][j]=(tuning*(UpperBound-Objective))/sqrt((gra[i][j]*gra[i][j])*(grb[i][j]*grb[i][j]));
                LRADum[i][j]=LRA[i][j]+stepsize[i][j]*gra[i][j];
                LRA[i][j]=LRADum[i][j];
                LRBDum[i][j]=LRB[i][j]+stepsize[i][j]*grb[i][j];
                LRB[i][j]=LRBDum[i][j];

            }
        }
    }

}

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I see two suspicious things in your code.

First, you are taking too much stack space (about ~40 MB).
Second, you are starting the index of the array at 1, where it should be 0:

for (int i=1; i<=noOfNodes; i++)

Change it to:

for (int i=0; i<noOfNodes; i++)

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At a guess, you have a stack overflow! You cannot reliably create gigantic arrays on the stack. You need to create them dynamically or statically.

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Where did you define noOfNodes? What is the initial value of this? Or, do you read this in from the console? If this is uninitialized, it probably has junk data -- which may or may not explain the crash.

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You need a stack of at least 40 megabytes to run this function because you're allocating five arrays of one million eight-byte doubles each.

Change the function to allocate the double arrays from the heap using new.

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You should really give us the whole code, e.g. noOfNodes is not defined anywhere.

Just a stab in the dark: are you possibly overflowing C since your indices (i and j) go from 1 to noOfNodes?

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First, what Neil said is true.

Second, C and C++ arrays start from index zero. If you declare

int a[100]; // 100 elements, from zeroth to ninety-ninth.

Then its elements are a[0], a[1] ... a[99].

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I can not see anything wrong with this code as given, BUT: You might have an off-by-one error if noOfNodes is 1000.

Remember that Arrays are 0-indexed so you have to access indexes 0 - 999 instead of 1 - 1000 as you are doing

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me too i have this problem and my function returned std::string now i just do reference an dreturn type void like that:

void readOnDicoFile(std::ifstream file/*If you have "using namespace std;" instruction, put ifstream, not std::ifstream (you can put both)*/)

and before:

std::string readOnDicoFile(std::string fileName/*If you have "using namespace std;" instruction, put ifstream, not std::ifstream (you can put both)*/)