SingleSource/Benchmarks/Polybench/linear-algebra/solvers/ludcmp/ludcmp.c

/**
 * ludcmp.c: This file is part of the PolyBench/C 3.2 test suite.
 *
 *
 * Contact: Louis-Noel Pouchet <pouchet@cse.ohio-state.edu>
 * Web address: http://polybench.sourceforge.net
 */
#include <stdio.h>
#include <unistd.h>
#include <string.h>
#include <math.h>

/* Include polybench common header. */
#include <polybench.h>

/* Include benchmark-specific header. */
/* Default data type is double, default size is 1024. */
#include "ludcmp.h"


/* Array initialization. */
static
void init_array (int n,
		 DATA_TYPE POLYBENCH_2D(A,N+1,N+1,n+1,n+1),
		 DATA_TYPE POLYBENCH_1D(b,N+1,n+1),
		 DATA_TYPE POLYBENCH_1D(x,N+1,n+1),
		 DATA_TYPE POLYBENCH_1D(y,N+1,n+1))
{
#pragma STDC FP_CONTRACT OFF
  int i, j;

  for (i = 0; i <= n; i++)
    {
      x[i] = i + 1;
      y[i] = (i+1)/n/2.0 + 1;
      b[i] = (i+1)/n/2.0 + 42;
      for (j = 0; j <= n; j++) {
	A[i][j] = ((DATA_TYPE) (i+1)*(j+1)) / n;
      }
    }
}


/* DCE code. Must scan the entire live-out data.
   Can be used also to check the correctness of the output. */
static
void print_array(int n,
		 DATA_TYPE POLYBENCH_1D(x,N+1,n+1))

{
  int i;

  for (i = 0; i <= n; i++) {
    fprintf (stderr, DATA_PRINTF_MODIFIER, x[i]);
    if (i % 20 == 0) fprintf (stderr, "\n");
  }
}


/* Main computational kernel. The whole function will be timed,
   including the call and return. */
static
void kernel_ludcmp(int n,
		   DATA_TYPE POLYBENCH_2D(A,N+1,N+1,n+1,n+1),
		   DATA_TYPE POLYBENCH_1D(b,N+1,n+1),
		   DATA_TYPE POLYBENCH_1D(x,N+1,n+1),
		   DATA_TYPE POLYBENCH_1D(y,N+1,n+1))
{
  int i, j, k;

  DATA_TYPE w;

#pragma scop
  b[0] = 1.0;
  for (i = 0; i < _PB_N; i++)
    {
      for (j = i+1; j <= _PB_N; j++)
        {
	  w = A[j][i];
	  for (k = 0; k < i; k++)
	    w = w- A[j][k] * A[k][i];
	  A[j][i] = w / A[i][i];
        }
      for (j = i+1; j <= _PB_N; j++)
        {
	  w = A[i+1][j];
	  for (k = 0; k <= i; k++)
	    w = w  - A[i+1][k] * A[k][j];
	  A[i+1][j] = w;
        }
    }
  y[0] = b[0];
  for (i = 1; i <= _PB_N; i++)
    {
      w = b[i];
      for (j = 0; j < i; j++)
	w = w - A[i][j] * y[j];
      y[i] = w;
    }
  x[_PB_N] = y[_PB_N] / A[_PB_N][_PB_N];
  for (i = 0; i <= _PB_N - 1; i++)
    {
      w = y[_PB_N - 1 - (i)];
      for (j = _PB_N - i; j <= _PB_N; j++)
	w = w - A[_PB_N - 1 - i][j] * x[j];
      x[_PB_N - 1 - i] = w / A[_PB_N - 1 - (i)][_PB_N - 1-(i)];
    }
#pragma endscop

}

static void
kernel_ludcmp_StrictFP(int n,
                       DATA_TYPE POLYBENCH_2D(A,N+1,N+1,n+1,n+1),
                       DATA_TYPE POLYBENCH_1D(b,N+1,n+1),
                       DATA_TYPE POLYBENCH_1D(x,N+1,n+1),
                       DATA_TYPE POLYBENCH_1D(y,N+1,n+1))
{
#pragma STDC FP_CONTRACT OFF
  int i, j, k;

  DATA_TYPE w;

  b[0] = 1.0;
  for (i = 0; i < _PB_N; i++)
    {
      for (j = i+1; j <= _PB_N; j++)
        {
	  w = A[j][i];
	  for (k = 0; k < i; k++)
	    w = w- A[j][k] * A[k][i];
	  A[j][i] = w / A[i][i];
        }
      for (j = i+1; j <= _PB_N; j++)
        {
	  w = A[i+1][j];
	  for (k = 0; k <= i; k++)
	    w = w  - A[i+1][k] * A[k][j];
	  A[i+1][j] = w;
        }
    }
  y[0] = b[0];
  for (i = 1; i <= _PB_N; i++)
    {
      w = b[i];
      for (j = 0; j < i; j++)
	w = w - A[i][j] * y[j];
      y[i] = w;
    }
  x[_PB_N] = y[_PB_N] / A[_PB_N][_PB_N];
  for (i = 0; i <= _PB_N - 1; i++)
    {
      w = y[_PB_N - 1 - (i)];
      for (j = _PB_N - i; j <= _PB_N; j++)
	w = w - A[_PB_N - 1 - i][j] * x[j];
      x[_PB_N - 1 - i] = w / A[_PB_N - 1 - (i)][_PB_N - 1-(i)];
    }
}

/* Return 0 when one of the elements of arrays A and B do not match within the
   allowed FP_ABSTOLERANCE.  Return 1 when all elements match.  */
static int
check_FP(int n,
         DATA_TYPE POLYBENCH_1D(A,N+1,n),
         DATA_TYPE POLYBENCH_1D(B,N+1,n)) {
  int i;
  double AbsTolerance = FP_ABSTOLERANCE;
  for (i = 0; i < _PB_N+1; i++)
    {
      double V1 = A[i];
      double V2 = B[i];
      double Diff = fabs(V1 - V2);
      if (Diff > AbsTolerance) {
        fprintf(stderr, "A[%d] = %lf and B[%d] = %lf differ more than"
                " FP_ABSTOLERANCE = %lf\n", i, V1, i, V2, AbsTolerance);
        return 0;
      }
    }

  return 1;
}

int main(int argc, char** argv)
{
  /* Retrieve problem size. */
  int n = N;

  /* Variable declaration/allocation. */
  POLYBENCH_2D_ARRAY_DECL(A, DATA_TYPE, N+1, N+1, n+1, n+1);
  POLYBENCH_1D_ARRAY_DECL(b, DATA_TYPE, N+1, n+1);
  POLYBENCH_1D_ARRAY_DECL(x, DATA_TYPE, N+1, n+1);
  POLYBENCH_1D_ARRAY_DECL(x_StrictFP, DATA_TYPE, N+1, n+1);
  POLYBENCH_1D_ARRAY_DECL(y, DATA_TYPE, N+1, n+1);


  /* Initialize array(s). */
  init_array (n,
	      POLYBENCH_ARRAY(A),
	      POLYBENCH_ARRAY(b),
	      POLYBENCH_ARRAY(x),
	      POLYBENCH_ARRAY(y));

  /* Start timer. */
  polybench_start_instruments;

  /* Run kernel. */
  kernel_ludcmp (n,
		 POLYBENCH_ARRAY(A),
		 POLYBENCH_ARRAY(b),
		 POLYBENCH_ARRAY(x),
		 POLYBENCH_ARRAY(y));

  /* Stop and print timer. */
  polybench_stop_instruments;
  polybench_print_instruments;

  init_array (n,
	      POLYBENCH_ARRAY(A),
	      POLYBENCH_ARRAY(b),
	      POLYBENCH_ARRAY(x_StrictFP),
	      POLYBENCH_ARRAY(y));
  kernel_ludcmp (n,
		 POLYBENCH_ARRAY(A),
		 POLYBENCH_ARRAY(b),
		 POLYBENCH_ARRAY(x_StrictFP),
		 POLYBENCH_ARRAY(y));
  if (!check_FP(n, POLYBENCH_ARRAY(x), POLYBENCH_ARRAY(x_StrictFP)))
    return 1;

  /* Prevent dead-code elimination. All live-out data must be printed
     by the function call in argument. */
  polybench_prevent_dce(print_array(n, POLYBENCH_ARRAY(x_StrictFP)));

  /* Be clean. */
  POLYBENCH_FREE_ARRAY(A);
  POLYBENCH_FREE_ARRAY(b);
  POLYBENCH_FREE_ARRAY(x);
  POLYBENCH_FREE_ARRAY(x_StrictFP);
  POLYBENCH_FREE_ARRAY(y);

  return 0;
}