OpenBLAS/lapack/potf2/potf2_L.c

/*********************************************************************/
/* Copyright 2009, 2010 The University of Texas at Austin.           */
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#include <stdio.h>
#include <math.h>
#include "common.h"

static FLOAT dm1 = -1.;
static FLOAT dp1 =  1.;

#ifndef SQRT
#define SQRT(x)	sqrt(x)
#endif

blasint CNAME(blas_arg_t *args, BLASLONG *range_m, BLASLONG *range_n, FLOAT *sa, FLOAT *sb, BLASLONG myid) {

  BLASLONG n, lda;
  FLOAT *a;

  FLOAT ajj;
  FLOAT *aoffset;
  BLASLONG i, j;

  n      = args -> n;
  a      = (FLOAT *)args -> a;
  lda    = args -> lda;

  if (range_n) {
    n      = range_n[1] - range_n[0];
    a     += range_n[0] * (lda + 1) * COMPSIZE;
  }

  aoffset = a;

  for (j = 0; j < n; j++) {

    ajj = *(aoffset + j) - DOTU_K(j, a + j, lda, a + j, lda);

    if (ajj <= 0){
      *(aoffset + j) = ajj;
      return j + 1;
    }
    ajj = SQRT(ajj);
    *(aoffset + j) = ajj;

    i = n - j - 1;

    if (i > 0) {
      GEMV_N(i, j, 0, dm1,
	     a + j + 1, lda,
	     a + j, lda,
	     aoffset + j + 1, 1, sb);

      SCAL_K(i, 0, 0, dp1 / ajj,
	     aoffset + j + 1, 1, NULL, 0, NULL, 0);
    }

    aoffset += lda;
  }

  return 0;
}