example_from_web.c

/* -*- Mode:C; Coding:us-ascii-unix; fill-column:132 -*- */
/* ****************************************************************************************************************************** */
/**
   @file      blas2C.c
   @author    Mitch Richling <http://www.mitchr.me/>
   @Copyright Copyright 1997 by Mitch Richling.  All rights reserved.
   @brief     Demonstrate several cblas (level 1) functions. @EOL
   @Keywords  blas cblas C fortran numerical linear algebra vector matrix gemv ger
   @Std       C89

   This is a simple program intended to illistrate how to make use of #gemv and #ger blas routines (as implimented in the cblas).
              
*/

/* ------------------------------------------------------------------------------------------------------------------------------ */

#include <math.h>               /* Math stuff      ISOC  */
#include <stdio.h>              /* I/O lib         ISOC  */
#include <stdlib.h>             /* Standard Lib    ISOC  */
#include <cblas.h>           /* Basic Linear Algebra I/O */

int main(int argc, char **argv) {
  double a[4*5] = {  1, 2, 3, 4, 5,
                     6, 7, 8, 9,10,
                    11,12,13,14,15,
                    16,17,18,19,20
                  };
  double x[5]  = {2,3,4,5,6};
  double y[4];

  // printMatrix(CblasRowMajor, 4, 5, a, 8, 3, NULL, NULL, NULL, NULL, NULL, "              a = ");
  // printVector(5, x, 8, 3, NULL, NULL, NULL, "              x = ");

           /* row_order      transform     lenY lenX alpha  a  lda  X  incX  beta  Y, incY */
  cblas_dgemv(CblasRowMajor, CblasNoTrans, 4,   5,   1,     a,   5, x, 1,    0,    y, 1);
  // printVector(4, y, 8, 3, NULL, NULL, NULL, "       y<-1.0*a*xT+0.0*y= ");

  int i;

  for(i = 0; i < 4; i++)
  {
    printf("%8.2f\n",y[i] );
  }

  printf("\n");


          /* row_order       lenY lenX alpha  X  incX  Y, incY A  LDA */
  cblas_dger(CblasRowMajor,  4,   5,   1,     y, 1,    x, 1,   a, 5);
  // printMatrix(CblasRowMajor, 4, 5, a, 8, 3, NULL, NULL, NULL, NULL, NULL, "a <- 1.0*x.yT+a = ");


  for(i = 0; i < 4*5; i++)
  {
    printf("%8.2f", a[i] );
    if ((i+1)%5 == 0)
    {
      printf("\n");
    }
  }
  return 0;
} /* end func main */