matrix-multiplication.c

#include <stdio.h>
#include <Accelerate/Accelerate.h>

int main(int argc, const char * argv[]) {

  double A[] = {
    1.0, 2.0, 3.0,
    4.0, 5.0, 6.0
  };

  double B[] = {
    1.0, 2.0,
    3.0, 4.0,
    5.0, 6.0
  };

  double C[] = {
    0.0, 0.0,
    0.0, 0.0
  };


  cblas_dgemm(
              CblasRowMajor,  // Order: row-major (C) data ordering (cf. column-major (Fortran)
              CblasNoTrans,   // TransA: whether to transpose matrix A
              CblasNoTrans,   // TransB: whether to transpose matrix B
              2,              // M: rows in A, C
              2,              // N: cols in B, C
              3,              // K: cols in A, rows in C
              1.0,            // alpha: scaling factor for product of A and B
              A,
              3,              // lda: size of first dimention of A (i.e. number of elements in first row?)
              B,
              2,              // ldb: size of first dimension of B (i.e. number of elements in first row?)
              1.0,            // beta: scaling factor for matrix C
              C,
              2               // ldc: size of the first dimension of C
              );

  printf("%.2f %.2f\n", C[0], C[1]);
  printf("%.2f %.2f\n", C[2], C[3]);

  return 0;
}