EXODUS/packages/seacas/libraries/chaco/eigen/splarax.c

/*
 * Copyright(C) 1999-2020, 2023 National Technology & Engineering Solutions
 * of Sandia, LLC (NTESS).  Under the terms of Contract DE-NA0003525 with
 * NTESS, the U.S. Government retains certain rights in this software.
 *
 * See packages/seacas/LICENSE for details
 */

#include "defs.h"
#include <stdio.h> // for NULL

/* Sparse linked A(matrix) times x(vector), double precision. */
void splarax(double           *result, /* result of matrix vector multiplication */
             struct vtx_data **mat,    /* graph data structure */
             int               n,      /* number of rows/columns in matrix */
             double           *vec,    /* vector being multiplied by matrix */
             double           *vwsqrt, /* square roots of vertex weights */
             double           *work    /* work vector from 1-n */
)
{
  extern int       PERTURB;     /* perturb matrix? */
  extern int       NPERTURB;    /* if so, number of edges to perturb */
  extern double    PERTURB_MAX; /* maximum value of perturbation */
  struct vtx_data *mat_i;       /* an entry in "mat" */
  double           sum;         /* sums inner product of matrix-row & vector */
  int             *colpntr;     /* loops through indices of nonzeros in a row */
  float           *wgtpntr;     /* loops through values of nonzeros */
  int              i, j;        /* loop counters */
  double          *wrkpntr;     /* loops through indices of work vector */
  double          *vwsqpntr;    /* loops through indices of vwsqrt */
  double          *vecpntr;     /* loops through indices of vec */
  double          *respntr;     /* loops through indices of result */
  int              last_edge;   /* last edge in edge list */

  if (vwsqrt == NULL) {          /* No vertex weights */
    if (mat[1]->ewgts == NULL) { /* No edge weights */
      respntr = result;
      for (i = 1; i <= n; i++) {
        mat_i     = mat[i];
        colpntr   = mat_i->edges;
        last_edge = mat_i->nedges - 1;
        sum       = last_edge * vec[*colpntr++];
        for (j = last_edge; j; j--) {
          sum -= vec[*colpntr++];
        }
        *(++respntr) = sum;
      }
    }
    else { /* Edge weights */
      respntr = result;
      for (i = 1; i <= n; i++) {
        mat_i   = mat[i];
        colpntr = mat_i->edges;
        wgtpntr = mat_i->ewgts;
        sum     = 0.0;
        for (j = mat_i->nedges; j; j--) {
          sum -= *wgtpntr++ * vec[*colpntr++];
        }
        *(++respntr) = sum; /* -sum if want -Ax */
      }
    }
    if (PERTURB && NPERTURB > 0 && PERTURB_MAX > 0.0) {
      perturb(result, vec);
    }
  }
  else { /* Vertex weights */
    wrkpntr  = work;
    vecpntr  = vec;
    vwsqpntr = vwsqrt;
    for (i = n; i; i--) {
      *(++wrkpntr) = *(++vecpntr) / *(++vwsqpntr);
    }

    if (mat[1]->ewgts == NULL) { /* No edge weights. */
      respntr = result;
      for (i = 1; i <= n; i++) {
        mat_i     = mat[i];
        colpntr   = mat_i->edges;
        last_edge = mat_i->nedges - 1;
        sum       = (last_edge)*work[*colpntr++];
        for (j = last_edge; j; j--) {
          sum -= work[*colpntr++];
        }
        *(++respntr) = sum;
      }
    }
    else { /* Edge weights. */
      respntr = result;
      for (i = 1; i <= n; i++) {
        mat_i   = mat[i];
        colpntr = mat_i->edges;
        wgtpntr = mat_i->ewgts;
        sum     = 0.0;
        for (j = mat_i->nedges; j; j--) {
          sum -= *wgtpntr++ * work[*colpntr++];
        }
        *(++respntr) = sum; /* -sum if want -Ax */
      }
    }
    if (PERTURB && NPERTURB > 0 && PERTURB_MAX > 0.0) {
      perturb(result, work);
    }

    respntr  = result;
    vwsqpntr = vwsqrt;
    for (i = n; i; i--) {
      *(++respntr) /= *(++vwsqpntr);
    }
  }
}

/* Sparse linked A(matrix) times x(vector)i, float version. */
void splarax_float(float            *result, /* result of matrix vector multiplication */
                   struct vtx_data **mat,    /* graph data structure */
                   int               n,      /* number of rows/columns in matrix */
                   float            *vec,    /* vector being multiplied by matrix */
                   float            *vwsqrt, /* square roots of vertex weights */
                   float            *work    /* work vector from 1-n */
)
{
  extern int       PERTURB;     /* perturb matrix? */
  extern int       NPERTURB;    /* if so, number of edges to perturb */
  extern double    PERTURB_MAX; /* maximum value of perturbation */
  struct vtx_data *mat_i;       /* an entry in "mat" */
  double           sum;         /* sums inner product of matrix-row & vector */
  int             *colpntr;     /* loops through indices of nonzeros in a row */
  float           *wgtpntr;     /* loops through values of nonzeros */
  int              i, j;        /* loop counters */
  float           *wrkpntr;     /* loops through indices of work vector */
  float           *vwsqpntr;    /* loops through indices of vwsqrt */
  float           *vecpntr;     /* loops through indices of vec */
  float           *respntr;     /* loops through indices of result */
  int              last_edge;   /* last edge in edge list */

  if (vwsqrt == NULL) {          /* No vertex weights */
    if (mat[1]->ewgts == NULL) { /* No edge weights */
      respntr = result;
      for (i = 1; i <= n; i++) {
        mat_i     = mat[i];
        colpntr   = mat_i->edges;
        last_edge = mat_i->nedges - 1;
        sum       = (last_edge)*vec[*colpntr++];
        for (j = last_edge; j; j--) {
          sum -= vec[*colpntr++];
        }
        *(++respntr) = sum;
      }
    }
    else { /* Edge weights */
      respntr = result;
      for (i = 1; i <= n; i++) {
        mat_i   = mat[i];
        colpntr = mat_i->edges;
        wgtpntr = mat_i->ewgts;
        sum     = 0.0;
        for (j = mat_i->nedges; j; j--) {
          sum -= *wgtpntr++ * vec[*colpntr++];
        }
        *(++respntr) = sum; /* -sum if want -Ax */
      }
    }
    if (PERTURB && NPERTURB > 0 && PERTURB_MAX > 0.0) {
      perturb_float(result, vec);
    }
  }
  else { /* Vertex weights */
    wrkpntr  = work;
    vecpntr  = vec;
    vwsqpntr = vwsqrt;
    for (i = n; i; i--) {
      *(++wrkpntr) = *(++vecpntr) / *(++vwsqpntr);
    }

    if (mat[1]->ewgts == NULL) { /* No edge weights. */
      respntr = result;
      for (i = 1; i <= n; i++) {
        mat_i     = mat[i];
        colpntr   = mat_i->edges;
        last_edge = mat_i->nedges - 1;
        sum       = (last_edge)*work[*colpntr++];
        for (j = last_edge; j; j--) {
          sum -= work[*colpntr++];
        }
        *(++respntr) = sum;
      }
    }
    else { /* Edge weights. */
      respntr = result;
      for (i = 1; i <= n; i++) {
        mat_i   = mat[i];
        colpntr = mat_i->edges;
        wgtpntr = mat_i->ewgts;
        sum     = 0.0;
        for (j = mat_i->nedges; j; j--) {
          sum -= *wgtpntr++ * work[*colpntr++];
        }
        *(++respntr) = sum; /* -sum if want -Ax */
      }
    }
    if (PERTURB && NPERTURB > 0 && PERTURB_MAX > 0.0) {
      perturb_float(result, work);
    }

    respntr  = result;
    vwsqpntr = vwsqrt;
    for (i = n; i; i--) {
      *(++respntr) /= *(++vwsqpntr);
    }
  }
}