Passing argument makes a pointer without cast? - c

Question

I'm having an issue with compling the code.
I keep getting these errors.
"C: 194 warning passing argument 3 of 'matrix_column_subtract' makes pointer from integer without a cast"
"C: 12 note: expected 'double**' but argument is type 'int'
"C: 194 error too few arguments to function 'matrix_column_subtract'
I think I know what is going on I'm calling matrix_column_multiply is a void and I need to be calling it a pointer pointer I think and I don't know how to chage that. If anyone has some idea on how I can get this to compile that would be highly appreciated!!
#include <stdio.h>
#include <stdlib.h>
#include <math.h>
#define DEBUG 0
#define MAX_ITER 10000
double *eigen (int n, double **A);
void qr_decomp (int n, double **A, double **Q, double **R);
void matrix_copy_column(double **msrc, int col1, double **mdst,int col2, int rows);
void matrix_column_subtract(double **m1, int c1, double **m2, int c2, int rows);
void matrix_column_multiply(double **m, int c, double k, int rows);
int main() {
int i, n = 126;
double *eig, **Am;
FILE *BinInp, *TxtOut;
/* Input Code: Reads bv, Am in binary form from CGrad.bin */
if ( (BinInp = fopen("CGrad.bin","r")) == NULL ) {
fprintf(stderr, "Cannot open matrix binary file INPUT... exiting\n");
exit(-1);
}
Am = (double**)malloc (n*sizeof(double*));
Am[0] = (double*)malloc (n*n*sizeof(double));
for (i = 1; i < n; ++i) {
Am[i] = Am[0] + i*n;
}
for (i = 0; i < n; i++) {
if (i==0) { /* Read one extra line that is discarded (bv is still in bin file) */
if (!fread(Am[i], sizeof(double), n, BinInp)) {
fprintf(stderr, "Cannot read row Am[%03d] of matrix... exiting\n", i+1);
exit(1);
}
}
if (!fread(Am[i], sizeof(double), n, BinInp)) {
fprintf(stderr, "Cannot read row Am[%03d] of matrix... exiting\n", i+1);
exit(1);
}
}
if (fclose(BinInp) == EOF) {
fprintf(stderr, "Cannot close matrix binary file INPUT... exiting\n");
exit(-1);
}
/* COMPUTE EIGENVALUES HERE USING FUNCTIONS. RETURN EIGENVALUES (AS 1D VECTOR) TO eig. */
if (DEBUG) printf ("Calling eigen\n");
eig = eigen (n, Am);
/* Output Code: Writes eig in text form to Eigs.txt */
if ( (TxtOut = fopen("Eigs.txt", "w")) == NULL ) {
fprintf(stderr, "Cannot open matrix text file OUTPUT... exiting\n");
exit(-1);
}
for (i = 0; i < n; i++) {
fprintf (TxtOut, "%18.14e ", eig[i]);
}
if (fclose(TxtOut) == EOF) {
fprintf(stderr, "Cannot close matrix text file INPUT... exiting\n");
exit(-1);
}
return 0;
}
double* eigen (int n, double **Acur)
{
double err = 1, eps = 1e-2;
double ndenom, nnumer, temp;
double *eig, **Anex, **Qsub, **Rsub;
int i, j, k, iters = 1;
/* Malloc memory for the three matricies */
Anex = malloc (n*sizeof(double*));
Anex[0] = malloc (n*n*sizeof(double));
for (i = 1; i < n; ++i) {
Anex[i] = Anex[0] + i*n;
}
Qsub = malloc (n*sizeof(double*));
Qsub[0] = malloc (n*n*sizeof(double));
for (i = 1; i < n; ++i) {
Qsub[i] = Qsub[0] + i*n;
}
Rsub = malloc (n*sizeof(double*));
Rsub[0] = malloc (n*n*sizeof(double));
for (i = 1; i < n; ++i) {
Rsub[i] = Rsub[0] + i*n;
}
/* Malloc memory for the return eig vector */
eig = malloc (n*sizeof(double));
for (i = 0; i < n; i++) {
eig[i] = 0;
}
/* Enter main iteration loop for eigenvalues */
while (err > eps && iters < MAX_ITER) {
/* QR Decompose Acur then find next iterate value in Anex */
qr_decomp (n, Acur, Qsub, Rsub);
// FIND NEXT ITERATE VALUE, PUT IN Anex.
/* Determine relative error change, reset "old" iterate value. */
ndenom = 0;
nnumer = 0;
for (i = 0; i < n; i++) {
for (j = 0; j < n; j++) {
temp = Anex[i][j]-Acur[i][j];
ndenom += temp*temp;
nnumer += Anex[i][j]*Anex[i][j];
Acur[i][j] = Anex[i][j];
}
}
err = sqrt(ndenom)/sqrt(nnumer);
/* Increment the iteration count and report error */
if (iters % 25 == 0) {
printf ("Error at end of iteration %05d = %14.10f %%\n", iters, 100*err);
}
++iters;
}
printf ("Error at end of iteration %05d = %14.10f\nCONVERGED.\n", iters-1, err);
if (iters == MAX_ITER) {
printf ("WARNING: MAX_ITER iterations reached!...\n");
}
/* Copy diagonal entries of Acur into eig for return to main */
for (i=0; i<n; i++) {
eig[i] = Acur[i][i];
}
return eig;
}
void qr_decomp (int n, double **Adec, double **myQ, double **myR)
{
int i, j, k; /* Loop Variables: this is all you should need! */
double **T, **S;
double r;
T = malloc (n*sizeof(double*));
T[0] = malloc (n*n*sizeof(double));
for (i = 1; i < n; ++i) {
T[i] = T[0] + i*n;
}
S = malloc (n*sizeof(double*));
S[0] = malloc (n*n*sizeof(double));
for (i = 1; i < n; ++i) {
S[i] = S[0] + i*n;
}
/* Main loop for decomposition */
for (i=0; i<n; i++) {
/* Column i of Q is initially column i of A */
matrix_copy_column(Adec,i,myQ,i,n);
/* For j < i-1, Perform the dot product between the j row of Q and the
i row of A to determine the R(j,i) value, then insure the Q i column
is orthogonal to all other Q columns by subtracting existing Q columns
from it. */
for (j = 0; j < i; j++) {
//r[j,i] = Qj^T * Ui
matrix_copy_column(myQ,j,T,0,n);
matrix_copy_column(Adec,i,S,0,n);
for (k=0; k<n; k++) {
r += T[k][0] * S[k][0];
}
/* Determine the R diagonal as the magnitude of the Q column, then
normalize the Q column (make it a unit vector). */
//Qi = Ui
myR[j][i] = r;
// Something wrong here.
// There is one parameter missing, as matrix_column_subtract needs 5 parameters and
// only 4 are given.
// Also, matrix_column_multiply is defined as returning a void, whereas the 3rd parameter
// of matrix_column_subtract should be a double **
matrix_column_subtract(myQ,i,matrix_column_multiply(T,0,r,n),j);
}
}
}
/* Copies a matrix column from msrc at column col1 to mdst at column col2 */
void matrix_copy_column(double **msrc, int col1, double **mdst,int col2, int rows) {
int i = 0;
for (i=0; i<rows; i++) {
mdst[i][col2] = msrc[i][col1];
}
}
/* Subtracts m2's column c2 from m1's column c1 */
void matrix_column_subtract(double **m1, int c1, double **m2, int c2, int rows) {
int i = 0;
for (i=0; i<rows; i++) {
m1[i][c1] -= m2[i][c2];
}
/*return m1;*/
}
void matrix_column_multiply(double **m, int c, double k, int rows) {
int i = 0;
for (i=0; i<rows; i++) {
m[i][c] *= k;
}
/*return m;*/
}

Answer 1

A problem is here.
matrix_column_subtract(myQ,i,matrix_column_multiply(T,0,r,n),j);
The relevant function signatures are:
void matrix_column_subtract(double **m1, int c1, double **m2, int c2, int rows);
void matrix_column_multiply(double **m, int c, double k, int rows);
Note that matrix_column_multiply returns void, but you're passing it in as if it were double **. I'm guessing the compiler is desperately trying to make it work and returned some sort of garbage integer.
These functions return void because they do their work directly on the matrix in question. matrix_column_multiply alters m. matrix_column_subtract alters m1.
To make it work, call matrix_column_multiply on T then pass T (now modified by the multiplication) into matrix_column_subtract.
matrix_column_multiply(T, 0, r, n);
matrix_column_subtract(myQ, i, T, j, ...rows...);
You're still missing the fifth argument, rows. I'm going to guess that's n, same as has been used for the rows in every other matrix_column_blah call.