compile OpenBLAS with INTERFACE64=1. clang/gcc -o test test_dgeqrt3_int64.c /your/path/libopenblas.a

test_dgeqrt3_int64.c

#include <stdio.h>
#include <stdlib.h>
#include <time.h>
#include <string.h>
extern void dgeqrt3_(long * m, long *n, double * a, long *lda, double *t, long *ldt, long*info);

int main(int argc, char**argv)
{
  int in, i;
  long n,info=1;
  int ct;
  double * a, *t, *ia;
  if(argc<=2){
    printf("Please input n and count\n");
    exit(1);
  }
  in=atoi(argv[1]);
  ct=atoi(argv[2]);
  n=in;

  a=(double*)malloc(n*n*sizeof(double));
  ia=(double*)malloc(n*n*sizeof(double));
  t=(double*)malloc(n*n*sizeof(double));
  
  srand((unsigned)time(NULL));


  if(a==NULL || t==NULL || ia==NULL){
    printf("memory alloc error!\n");
    exit(1);
  }

  for (i=0; i<n*n; i++){
    ia[i] = (rand()%100)/10.0;
    t[i]=0.0;
  }

  for (i = 0; i < ct; i++) {
    memcpy(a,ia,n*n*sizeof(double));
    dgeqrt3_(&n, &n, a, &n, t, &n, &info);
    if (i % 10 == 0) printf("Iteration %d\n", i);
  }

  printf("%ld\n",info);
  
  free(a);
  free(t);
  return 0;
}