hpc-2022-g3/OpenMP/linear-algebra/solvers/ludcmp/ludcmp.c

#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))
{
  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;

  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)];
  }
}

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(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;

  /* 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)));

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

  return 0;
}