2d array as function parameter problem, help appreciated.
I have been tinkering with this for a few hours and even with any examples can not find a reason for the Seg fault I'm getting, The code is all the way at the bottom of the post.
I am still new to C after a long python stint. I am trying to implement a jacobian algorithm to find the solution to a system of equations.
the header of the Jacobi dunction is commented right now to only take the array, and the length(it is assumed to be square)
the program dies on a segfault, running gdb gave me that it dies right at
Code:
aInv[xCounter][xCounter] = 1.0/A[xCounter][xCounter];
when i started with this program I hardcoded A right into the function and it went through no problems so this must be with the way im taking in and handling A.
Im sure the solution isnt terribly difficult but i've exhausted any similar examples I could find and hopefully someone here can offer guidance.
Code:
#include <stdio.h>
#include <math.h>
#include <stdlib.h>
int Jacobi(double **A/*,double *b*/,int n/*,double *xo,double tol,int MaxIt*/){
/*
USAGE:its = Jacobi(A,b,n,xo,tol,MaxIt);
INPUTS:A coefficient matrix for linear system
b right-hand side vector
n number of equations
xo vector containing initial guess
tol error tolerance-between successive approximations
MaxIt maximum number of iterations
OUTPUT:
its No.of iterations performed(return-1 if max exceeded)
xo approximate solution
*/
breakpt();
int iterCount = 0;
int i = 0;
int j = 0;
double tempDouble = 0;
/*First we find A^-1 */
double aInv[n][n];
int xCounter = 0;
int yCounter = 0;
double lower[n][n];
double upper[n][n];
while(yCounter < n){
xCounter = 0;
while(xCounter < n){
if(yCounter == xCounter){
printf("%f - a number",&A[xCounter][xCounter]);
aInv[xCounter][xCounter] = 1.0/A[xCounter][xCounter];
lower[xCounter][xCounter] = 0;
upper[xCounter][xCounter] = 0;
}
else{
aInv[xCounter][yCounter] = 0;
if(xCounter < yCounter){
lower[xCounter][yCounter] = A[xCounter][yCounter];
upper[xCounter][yCounter] = 0;
}
else{
upper[xCounter][yCounter] = A[xCounter][yCounter];
lower[xCounter][yCounter] = 0;
}
}
xCounter++;
}
yCounter++;
}
xCounter = 0;
PrintArray(aInv,2,"inverse");
PrintArray(lower,2,"lower");
PrintArray(upper,2,"upper");
/* while (counter < MaxIt){
}*/
}
int main(int argc, char *argv[]){
printf("GOT HERE");
double a[2][2] = {2,3,5,7};
Jacobi(&a,2);
}
/*Prints a 2d square array of double, for debugging purposes*/
void PrintArray(double** Arr, int size, char* name){
int counterX = 0;
int counterY = 0;
printf("Printing %s Array...",name);
while(counterY < size){
while(counterX < size){
printf("%f",Arr[counterX][counterY]);
counterX++;
}
printf("\n");
counterY++;
}
}
int breakpt(){
return 1;
}
