GE (C)

#include <stdio.h>
#include <stdlib.h>

int ge_fw(float *, int, int, float *);
int ge_bw(float *, int, int, float *);

int main(void) {
   int rows,cols,x,y = 0;
   float *i, *out, *outF = NULL;
   rows = 3;
   cols = 3;
   i = (float *)malloc(sizeof(float)*rows*cols);
   out = (float *)malloc(sizeof(float)*rows*cols);
   outF = (float *)malloc(sizeof(float)*rows*cols);
   /* Set vals for initial Matrix */
   i[0] = 1;
   i[1] = 1;
   i[2] = 0;
   i[3] = 1;
   i[4] = 1;
   i[5] = 4;
   i[6] = 1;
   i[7] = 1;
   i[8] = 8;
   ge_fw(i, rows, cols, out);
   ge_bw(out, rows, cols, outF);
   for (x=0; x < rows; x++) {
      for (y=0; y < cols; y++) {
         printf("%f ", i[x*cols + y]);
      }
      printf("\n");
   }
   printf("\n");
   for (x=0; x < rows; x++) {
      for (y=0; y < cols; y++) {
         printf("%f ", outF[x*cols + y]);
      }
      printf("\n");
   }
   return 0;
}

int ge_fw(float *u, int rows, int cols, float *m) {
   int r,c,x,v = 0;
   int toggle = 1; /* Toggle used twice to save an int (why not) */
   float scale,temp = 0;
   /* Error Check */
   if ((u == NULL) || (m == NULL)) { printf("The array must be allocated for assignment"); return -1; }
   /* Duplicate */
   for (x=0; x<rows*cols; x++) {
      m[x] = u[x];
   }
   /* Begin GE */
   for (c=0; c < rows; c++) {
      /* Swap rows if zero */
      toggle = 1;
      if (m[c*cols + c] == 0) {
         toggle = 0;
         for (x=c+1;x<rows;x++) {
            if (m[x*cols + c] != 0) {
               /* Execute the swap */
               for (v=0; v<cols; v++) {
                  temp = m[c*cols + v];
                  m[c*cols + v] = m[x*cols + v];
                  m[x*cols + v] = temp;
               }
               toggle = 1;
               break;
            }
         }
      }
      if (toggle == 0) { continue; } /* Skip zeros column */
      /* Assign values */
      for (r=c+1;r<rows;r++) {
         scale = m[r*cols + c]/m[c*cols + c];
         for (v=c; v < cols; v++) {
            m[r*cols + v] = m[r*cols + v] - scale*m[c*cols + v];
         }
      }
      /* Check for zero rows */
      for (r=c; r<rows; r++) {
         toggle = 1;
         for (x=0; x<cols; x++) {
            if (m[r*cols + x] != 0) { toggle = 0; break; }
         }
         if (toggle == 1) {
         /* Put zero row on bottom */
            for (v=r*cols; v<(rows-1)*cols; v++) {
               m[v] = m[v + cols];
            }
            for (v=(rows-1)*cols; v<rows*cols; v++) {
               m[v] = 0;
            }
         }
      }
   }
   return 0;
}

int ge_bw(float *u, int rows, int cols, float *m) {
   int r,c,x,v = 0;
   int toggle = 1;
   float scale,temp = 0;
   /* Error Checking */
   if ((u == NULL) || (m == NULL)) { printf("The array must be allocated for assignment"); return -1; }
   /* Duplicate */
   for (x=0; x<rows*cols; x++) {
      m[x] = u[x];
   }
   /* Begin Reverse GE */
   /* Check for zero rows */
   for (r=c; r<rows; r++) {
      toggle = 1;
      for (x=0; x<cols; x++) {
         if (m[r*cols + x] != 0) { toggle = 0; break; }
      }
      if (toggle == 1) {
      /* Check Zero rows bottom */
         break;
      }
   }
   if (r >= rows) { r = rows - 1; }
   for (c=r; c>=0; c--) {
      for (x=c-1; x >= 0; x--) {
         if (m[c*cols + c] == 0) { continue; }
         scale = m[x*cols + c]/m[c*cols + c];
         for (v=c; v<cols; v++) {
            m[x*cols + v] = m[x*cols + v] - scale*m[c*cols + v];
         }
      }
      if (m[c*cols + c] == 0) { continue; }
      scale = 1/m[c*cols + c];
      for (v=0; v<cols; v++) {
         m[c*cols + v] = scale*m[c*cols + v];
      }
   }
   /* Check for zero rows */
   for (r=c; r<rows; r++) {
      toggle = 1;
      for (x=0; x<cols; x++) {
         if (m[r*cols + x] != 0) { toggle = 0; break; }
      }
      if (toggle == 1) {
      /* Put zero row on bottom */
         for (v=r*cols; v<(rows-1)*cols; v++) {
            m[v] = m[v + cols];
         }
         for (v=(rows-1)*cols; v<rows*cols; v++) {
            m[v] = 0;
         }
      }
   }
   return 0;
}