Displaying 2 results from an estimated 2 matches for "printmatrix".
2013 Dec 06
3
Matrix memory layout R vs. C
...in R, it's a concatenation
of the columns. That leads to the problem. that an R-matrix, for example
123
456
789
is seen by C as
147
258
369
and vice versa.
Here's an example of C code that simply prints the matrix it gets from R:
#include <stdlib.h>
#include "R.h"
void printMatrix(int *mPtr, int *m, int *n) {
int (*matrix)[*n] = mPtr;
int j,k;
for(j = 0; j < *m; j++){
for(k = 0; k < *n; k++) {
printf("%d", matrix[j][k]);
}
printf("\n");
}
}
And here's what happens when I call the function in R:
> m <- 3;...
2010 Jan 23
1
matrix to a C function
Hi the list,
Is there a way to give a matrix to a C function, and then to use it as a
matrix ?
I write a function to print a matrix, but I use it as a vector :
1. void printMatrix(double *mTraj,int *nbCol, int *nbLigne){
2. int i=0,j=0;
3. for(i=0 ; i < *nbLigne ; i++){
4. for(j=0 ; j < *nbCol ; j++){
5. Rprintf(" %f",mTraj[i * *nbCol + j]);
6. }
7. Rprintf("\n");
8. }
9. }
I would like to use it as a matrix (line 5...