blob: 843f12a8baf25d906dd423d012eda3ee6c566b9e [file] [log] [blame]
/*
* Copyright 2013 The Emscripten Authors. All rights reserved.
* Emscripten is available under two separate licenses, the MIT license and the
* University of Illinois/NCSA Open Source License. Both these licenses can be
* found in the LICENSE file.
*/
/* gcc linpack.c cpuidc64.o cpuida64.o -m64 -lrt -lc -lm -o linpack
*
* Linpack 100x100 Benchmark In C/C++ For PCs
*
* Different compilers can produce different floating point numeric
* results, probably due to compiling instructions in a different
* sequence. As the program checks these, they may need to be changed.
* The log file indicates non-standard results and these values can
* be copied and pasted into this program. See // Values near the
* end of main().
*
* Different compilers do not optimise the code in the same way.
* This can lead to wide variations in benchmark speeds. See results
* with MS6 compiler ID and compare with those from same CPUs from
* the Watcom compiler generated code.
*
***************************************************************************
*/
#define _CRT_SECURE_NO_WARNINGS 1
#ifdef WIN32
#include <Windows.h>
#else
#include <sys/time.h>
#endif
#define UNROLL
#ifndef SP
#define DP
#endif
#ifdef SP
#define REAL float
#define ZERO 0.0
#define ONE 1.0
#define PREC "Single"
#endif
#ifdef DP
#define REAL double
#define ZERO 0.0e0
#define ONE 1.0e0
#define PREC "Double"
#endif
#ifdef ROLL
#define ROLLING "Rolled"
#endif
#ifdef UNROLL
#define ROLLING "Unrolled"
#endif
// VERSION
#ifdef CNNT
#define options "Non-optimised"
#define opt "0"
#else
// #define options "Optimised"
#define options "Opt 3 64 Bit"
#define opt "1"
#endif
#define NTIMES 10
#include <stdio.h>
#include <math.h>
#include <stdlib.h>
#include <time.h>
/* this is truly rank, but it's minimally invasive, and lifted in part from the STREAM scores */
static double secs;
#ifndef WIN32
double mysecond()
{
struct timeval tp;
struct timezone tzp;
int i;
i = gettimeofday(&tp,&tzp);
return ( (double) tp.tv_sec + (double) tp.tv_usec * 1.e-6 );
}
#else
double mysecond()
{
static LARGE_INTEGER freq = {0};
LARGE_INTEGER count = {0};
if(freq.QuadPart == 0LL) {
QueryPerformanceFrequency(&freq);
}
QueryPerformanceCounter(&count);
return (double)count.QuadPart / (double)freq.QuadPart;
}
#endif
void start_time()
{
secs = mysecond();
}
void end_time()
{
secs = mysecond() - secs;
}
void print_time (int row);
void matgen (REAL a[], int lda, int n, REAL b[], REAL *norma);
void dgefa (REAL a[], int lda, int n, int ipvt[], int *info);
void dgesl (REAL a[],int lda,int n,int ipvt[],REAL b[],int job);
void dmxpy (int n1, REAL y[], int n2, int ldm, REAL x[], REAL m[]);
void daxpy (int n, REAL da, REAL dx[], int incx, REAL dy[], int incy);
REAL epslon (REAL x);
int idamax (int n, REAL dx[], int incx);
void dscal (int n, REAL da, REAL dx[], int incx);
REAL ddot (int n, REAL dx[], int incx, REAL dy[], int incy);
static REAL atime[9][15];
double runSecs = 1;
int main (int argc, char *argv[])
{
static REAL aa[200*200],a[200*201],b[200],x[200];
REAL cray,ops,total,norma,normx;
REAL resid,residn,eps,tm2,epsn,x1,x2;
REAL mflops;
static int ipvt[200],n,i,j,ntimes,info,lda,ldaa;
int endit, pass, loop;
REAL overhead1, overhead2, time2;
REAL max1, max2;
char was[5][20];
char expect[5][20];
char title[5][20];
int errors;
int arg = argc > 1 ? argv[1][0] - '0' : 3;
if (arg == 0) return 0;
printf("\n");
printf("##########################################\n");
lda = 201;
ldaa = 200;
cray = .056;
n = 100;
fprintf(stdout, "%s ", ROLLING);
fprintf(stdout, "%s ", PREC);
fprintf(stdout,"Precision Linpack Benchmark - PC Version in 'C/C++'\n\n");
fprintf(stdout,"Optimisation %s\n\n",options);
ops = (2.0e0*(n*n*n))/3.0 + 2.0*(n*n);
matgen(a,lda,n,b,&norma);
start_time();
dgefa(a,lda,n,ipvt,&info);
end_time();
atime[0][0] = secs;
start_time();
dgesl(a,lda,n,ipvt,b,0);
end_time();
atime[1][0] = secs;
total = atime[0][0] + atime[1][0];
/* compute a residual to verify results. */
for (i = 0; i < n; i++) {
x[i] = b[i];
}
matgen(a,lda,n,b,&norma);
for (i = 0; i < n; i++) {
b[i] = -b[i];
}
dmxpy(n,b,n,lda,x,a);
resid = 0.0;
normx = 0.0;
for (i = 0; i < n; i++) {
resid = (resid > fabs((double)b[i]))
? resid : fabs((double)b[i]);
normx = (normx > fabs((double)x[i]))
? normx : fabs((double)x[i]);
}
eps = epslon(ONE);
residn = resid/( n*norma*normx*eps );
epsn = eps;
x1 = x[0] - 1;
x2 = x[n-1] - 1;
printf("norm resid resid machep");
printf(" x[0]-1 x[n-1]-1\n");
printf("%6.1f %17.8e%17.8e%17.8e%17.8e\n\n",
(double)residn, (double)resid, (double)epsn,
(double)x1, (double)x2);
printf("Times are reported for matrices of order %5d\n",n);
printf("1 pass times for array with leading dimension of%5d\n\n",lda);
printf(" dgefa dgesl total Mflops unit");
printf(" ratio\n");
atime[2][0] = total;
if (total > 0.0)
{
atime[3][0] = ops/(1.0e6*total);
atime[4][0] = 2.0/atime[3][0];
}
else
{
atime[3][0] = 0.0;
atime[4][0] = 0.0;
}
atime[5][0] = total/cray;
print_time(0);
/************************************************************************
* Calculate overhead of executing matgen procedure *
************************************************************************/
printf("\nCalculating matgen overhead\n");
pass = -20;
loop = NTIMES;
do
{
start_time();
pass = pass + 1;
for ( i = 0 ; i < loop ; i++)
{
matgen(a,lda,n,b,&norma);
}
end_time();
overhead1 = secs;
printf("%10d times %6.2f seconds\n", loop, overhead1);
if (overhead1 > runSecs)
{
pass = 0;
}
if (pass < 0)
{
if (overhead1 < 0.1)
{
loop = loop * 10;
}
else
{
loop = loop * 2;
}
}
}
while (pass < 0);
overhead1 = overhead1 / (double)loop;
printf("Overhead for 1 matgen %12.5f seconds\n\n", overhead1);
/************************************************************************
* Calculate matgen/dgefa passes for runSecs seconds *
************************************************************************/
printf("Calculating matgen/dgefa passes for %d seconds\n", (int)runSecs);
pass = -20;
ntimes = NTIMES;
do
{
start_time();
pass = pass + 1;
for ( i = 0 ; i < ntimes ; i++)
{
matgen(a,lda,n,b,&norma);
dgefa(a,lda,n,ipvt,&info );
}
end_time();
time2 = secs;
printf("%10d times %6.2f seconds\n", ntimes, time2);
if (time2 > runSecs)
{
pass = 0;
}
if (pass < 0)
{
if (time2 < 0.1)
{
ntimes = ntimes * 10;
}
else
{
ntimes = ntimes * 2;
}
}
}
while (pass < 0);
ntimes = (int)(runSecs * (double)ntimes / time2);
if (ntimes == 0) ntimes = 1;
printf("Passes used %10d \n\n", ntimes);
printf("Times for array with leading dimension of%4d\n\n",lda);
printf(" dgefa dgesl total Mflops unit");
printf(" ratio\n");
/************************************************************************
* Execute 5 passes *
************************************************************************/
tm2 = ntimes * overhead1;
atime[3][6] = 0;
for (j=1 ; j<6 ; j++)
{
start_time();
for (i = 0; i < ntimes; i++)
{
matgen(a,lda,n,b,&norma);
dgefa(a,lda,n,ipvt,&info );
}
end_time();
atime[0][j] = (secs - tm2)/ntimes;
start_time();
for (i = 0; i < ntimes; i++)
{
dgesl(a,lda,n,ipvt,b,0);
}
end_time();
atime[1][j] = secs/ntimes;
total = atime[0][j] + atime[1][j];
atime[2][j] = total;
atime[3][j] = ops/(1.0e6*total);
atime[4][j] = 2.0/atime[3][j];
atime[5][j] = total/cray;
atime[3][6] = atime[3][6] + atime[3][j];
print_time(j);
}
atime[3][6] = atime[3][6] / 5.0;
printf("Average %11.2f\n",
(double)atime[3][6]);
printf("\nCalculating matgen2 overhead\n");
/************************************************************************
* Calculate overhead of executing matgen procedure *
************************************************************************/
start_time();
for ( i = 0 ; i < loop ; i++)
{
matgen(aa,ldaa,n,b,&norma);
}
end_time();
overhead2 = secs;
overhead2 = overhead2 / (double)loop;
printf("Overhead for 1 matgen %12.5f seconds\n\n", overhead2);
printf("Times for array with leading dimension of%4d\n\n",ldaa);
printf(" dgefa dgesl total Mflops unit");
printf(" ratio\n");
/************************************************************************
* Execute 5 passes *
************************************************************************/
tm2 = ntimes * overhead2;
atime[3][12] = 0;
for (j=7 ; j<12 ; j++)
{
start_time();
for (i = 0; i < ntimes; i++)
{
matgen(aa,ldaa,n,b,&norma);
dgefa(aa,ldaa,n,ipvt,&info );
}
end_time();
atime[0][j] = (secs - tm2)/ntimes;
start_time();
for (i = 0; i < ntimes; i++)
{
dgesl(aa,ldaa,n,ipvt,b,0);
}
end_time();
atime[1][j] = secs/ntimes;
total = atime[0][j] + atime[1][j];
atime[2][j] = total;
atime[3][j] = ops/(1.0e6*total);
atime[4][j] = 2.0/atime[3][j];
atime[5][j] = total/cray;
atime[3][12] = atime[3][12] + atime[3][j];
print_time(j);
}
atime[3][12] = atime[3][12] / 5.0;
printf("Average %11.2f\n",
(double)atime[3][12]);
/************************************************************************
* Use minimum average as overall Mflops rating *
************************************************************************/
mflops = atime[3][6];
if (atime[3][12] < mflops) mflops = atime[3][12];
printf("\n");
printf( "%s ", ROLLING);
printf( "%s ", PREC);
printf(" Precision %11.2f Mflops \n\n",mflops);
max1 = 0;
for (i=1 ; i<6 ; i++)
{
if (atime[3][i] > max1) max1 = atime[3][i];
}
max2 = 0;
for (i=7 ; i<12 ; i++)
{
if (atime[3][i] > max2) max2 = atime[3][i];
}
if (max1 < max2) max2 = max1;
sprintf(was[0], "%16.1f",(double)residn);
sprintf(was[1], "%16.8e",(double)resid);
sprintf(was[2], "%16.8e",(double)epsn);
sprintf(was[3], "%16.8e",(double)x1);
sprintf(was[4], "%16.8e",(double)x2);
/*
// Values for Watcom
sprintf(expect[0], " 0.4");
sprintf(expect[1], " 7.41628980e-014");
sprintf(expect[2], " 1.00000000e-015");
sprintf(expect[3], "-1.49880108e-014");
sprintf(expect[4], "-1.89848137e-014");
// Values for Visual C++
sprintf(expect[0], " 1.7");
sprintf(expect[1], " 7.41628980e-014");
sprintf(expect[2], " 2.22044605e-016");
sprintf(expect[3], "-1.49880108e-014");
sprintf(expect[4], "-1.89848137e-014");
// Values for Ubuntu GCC 32 Bit
sprintf(expect[0], " 1.9");
sprintf(expect[1], " 8.39915160e-14");
sprintf(expect[2], " 2.22044605e-16");
sprintf(expect[3], " -6.22835117e-14");
sprintf(expect[4], " -4.16333634e-14");
*/
// Values for Ubuntu GCC 32 Bit
sprintf(expect[0], " 1.7");
sprintf(expect[1], " 7.41628980e-14");
sprintf(expect[2], " 2.22044605e-16");
sprintf(expect[3], " -1.49880108e-14");
sprintf(expect[4], " -1.89848137e-14");
sprintf(title[0], "norm. resid");
sprintf(title[1], "resid ");
sprintf(title[2], "machep ");
sprintf(title[3], "x[0]-1 ");
sprintf(title[4], "x[n-1]-1 ");
if (strtol(opt, NULL, 10) == 0)
{
sprintf(expect[2], " 8.88178420e-016");
}
errors = 0;
printf ("\n");
}
/*----------------------*/
void print_time (int row)
{
printf("%11.5f%11.5f%11.5f%11.2f%11.4f%11.4f\n", (double)atime[0][row],
(double)atime[1][row], (double)atime[2][row], (double)atime[3][row],
(double)atime[4][row], (double)atime[5][row]);
return;
}
/*----------------------*/
void matgen (REAL a[], int lda, int n, REAL b[], REAL *norma)
/* We would like to declare a[][lda], but c does not allow it. In this
function, references to a[i][j] are written a[lda*i+j]. */
{
int init, i, j;
init = 1325;
*norma = 0.0;
for (j = 0; j < n; j++) {
for (i = 0; i < n; i++) {
init = 3125*init % 65536;
a[lda*j+i] = (init - 32768.0)/16384.0;
*norma = (a[lda*j+i] > *norma) ? a[lda*j+i] : *norma;
/* alternative for some compilers
if (fabs(a[lda*j+i]) > *norma) *norma = fabs(a[lda*j+i]);
*/
}
}
for (i = 0; i < n; i++) {
b[i] = 0.0;
}
for (j = 0; j < n; j++) {
for (i = 0; i < n; i++) {
b[i] = b[i] + a[lda*j+i];
}
}
return;
}
/*----------------------*/
void dgefa(REAL a[], int lda, int n, int ipvt[], int *info)
/* We would like to declare a[][lda], but c does not allow it. In this
function, references to a[i][j] are written a[lda*i+j]. */
/*
dgefa factors a double precision matrix by gaussian elimination.
dgefa is usually called by dgeco, but it can be called
directly with a saving in time if rcond is not needed.
(time for dgeco) = (1 + 9/n)*(time for dgefa) .
on entry
a REAL precision[n][lda]
the matrix to be factored.
lda integer
the leading dimension of the array a .
n integer
the order of the matrix a .
on return
a an upper triangular matrix and the multipliers
which were used to obtain it.
the factorization can be written a = l*u where
l is a product of permutation and unit lower
triangular matrices and u is upper triangular.
ipvt integer[n]
an integer vector of pivot indices.
info integer
= 0 normal value.
= k if u[k][k] .eq. 0.0 . this is not an error
condition for this subroutine, but it does
indicate that dgesl or dgedi will divide by zero
if called. use rcond in dgeco for a reliable
indication of singularity.
linpack. this version dated 08/14/78 .
cleve moler, university of new mexico, argonne national lab.
functions
blas daxpy,dscal,idamax
*/
{
/* internal variables */
REAL t;
int j,k,kp1,l,nm1;
/* gaussian elimination with partial pivoting */
*info = 0;
nm1 = n - 1;
if (nm1 >= 0) {
for (k = 0; k < nm1; k++) {
kp1 = k + 1;
/* find l = pivot index */
l = idamax(n-k,&a[lda*k+k],1) + k;
ipvt[k] = l;
/* zero pivot implies this column already
triangularized */
if (a[lda*k+l] != ZERO) {
/* interchange if necessary */
if (l != k) {
t = a[lda*k+l];
a[lda*k+l] = a[lda*k+k];
a[lda*k+k] = t;
}
/* compute multipliers */
t = -ONE/a[lda*k+k];
dscal(n-(k+1),t,&a[lda*k+k+1],1);
/* row elimination with column indexing */
for (j = kp1; j < n; j++) {
t = a[lda*j+l];
if (l != k) {
a[lda*j+l] = a[lda*j+k];
a[lda*j+k] = t;
}
daxpy(n-(k+1),t,&a[lda*k+k+1],1,
&a[lda*j+k+1],1);
}
}
else {
*info = k;
}
}
}
ipvt[n-1] = n-1;
if (a[lda*(n-1)+(n-1)] == ZERO) *info = n-1;
return;
}
/*----------------------*/
void dgesl(REAL a[],int lda,int n,int ipvt[],REAL b[],int job )
/* We would like to declare a[][lda], but c does not allow it. In this
function, references to a[i][j] are written a[lda*i+j]. */
/*
dgesl solves the double precision system
a * x = b or trans(a) * x = b
using the factors computed by dgeco or dgefa.
on entry
a double precision[n][lda]
the output from dgeco or dgefa.
lda integer
the leading dimension of the array a .
n integer
the order of the matrix a .
ipvt integer[n]
the pivot vector from dgeco or dgefa.
b double precision[n]
the right hand side vector.
job integer
= 0 to solve a*x = b ,
= nonzero to solve trans(a)*x = b where
trans(a) is the transpose.
on return
b the solution vector x .
error condition
a division by zero will occur if the input factor contains a
zero on the diagonal. technically this indicates singularity
but it is often caused by improper arguments or improper
setting of lda . it will not occur if the subroutines are
called correctly and if dgeco has set rcond .gt. 0.0
or dgefa has set info .eq. 0 .
to compute inverse(a) * c where c is a matrix
with p columns
dgeco(a,lda,n,ipvt,rcond,z)
if (!rcond is too small){
for (j=0,j<p,j++)
dgesl(a,lda,n,ipvt,c[j][0],0);
}
linpack. this version dated 08/14/78 .
cleve moler, university of new mexico, argonne national lab.
functions
blas daxpy,ddot
*/
{
/* internal variables */
REAL t;
int k,kb,l,nm1;
nm1 = n - 1;
if (job == 0) {
/* job = 0 , solve a * x = b
first solve l*y = b */
if (nm1 >= 1) {
for (k = 0; k < nm1; k++) {
l = ipvt[k];
t = b[l];
if (l != k){
b[l] = b[k];
b[k] = t;
}
daxpy(n-(k+1),t,&a[lda*k+k+1],1,&b[k+1],1 );
}
}
/* now solve u*x = y */
for (kb = 0; kb < n; kb++) {
k = n - (kb + 1);
b[k] = b[k]/a[lda*k+k];
t = -b[k];
daxpy(k,t,&a[lda*k+0],1,&b[0],1 );
}
}
else {
/* job = nonzero, solve trans(a) * x = b
first solve trans(u)*y = b */
for (k = 0; k < n; k++) {
t = ddot(k,&a[lda*k+0],1,&b[0],1);
b[k] = (b[k] - t)/a[lda*k+k];
}
/* now solve trans(l)*x = y */
if (nm1 >= 1) {
for (kb = 1; kb < nm1; kb++) {
k = n - (kb+1);
b[k] = b[k] + ddot(n-(k+1),&a[lda*k+k+1],1,&b[k+1],1);
l = ipvt[k];
if (l != k) {
t = b[l];
b[l] = b[k];
b[k] = t;
}
}
}
}
return;
}
/*----------------------*/
void daxpy(int n, REAL da, REAL dx[], int incx, REAL dy[], int incy)
/*
constant times a vector plus a vector.
jack dongarra, linpack, 3/11/78.
*/
{
int i,ix,iy,m,mp1;
mp1 = 0;
m = 0;
if(n <= 0) return;
if (da == ZERO) return;
if(incx != 1 || incy != 1) {
/* code for unequal increments or equal increments
not equal to 1 */
ix = 0;
iy = 0;
if(incx < 0) ix = (-n+1)*incx;
if(incy < 0)iy = (-n+1)*incy;
for (i = 0;i < n; i++) {
dy[iy] = dy[iy] + da*dx[ix];
ix = ix + incx;
iy = iy + incy;
}
return;
}
/* code for both increments equal to 1 */
#ifdef ROLL
for (i = 0;i < n; i++) {
dy[i] = dy[i] + da*dx[i];
}
#endif
#ifdef UNROLL
m = n % 4;
if ( m != 0) {
for (i = 0; i < m; i++)
dy[i] = dy[i] + da*dx[i];
if (n < 4) return;
}
for (i = m; i < n; i = i + 4) {
dy[i] = dy[i] + da*dx[i];
dy[i+1] = dy[i+1] + da*dx[i+1];
dy[i+2] = dy[i+2] + da*dx[i+2];
dy[i+3] = dy[i+3] + da*dx[i+3];
}
#endif
return;
}
/*----------------------*/
REAL ddot(int n, REAL dx[], int incx, REAL dy[], int incy)
/*
forms the dot product of two vectors.
jack dongarra, linpack, 3/11/78.
*/
{
REAL dtemp;
int i,ix,iy,m,mp1;
mp1 = 0;
m = 0;
dtemp = ZERO;
if(n <= 0) return(ZERO);
if(incx != 1 || incy != 1) {
/* code for unequal increments or equal increments
not equal to 1 */
ix = 0;
iy = 0;
if (incx < 0) ix = (-n+1)*incx;
if (incy < 0) iy = (-n+1)*incy;
for (i = 0;i < n; i++) {
dtemp = dtemp + dx[ix]*dy[iy];
ix = ix + incx;
iy = iy + incy;
}
return(dtemp);
}
/* code for both increments equal to 1 */
#ifdef ROLL
for (i=0;i < n; i++)
dtemp = dtemp + dx[i]*dy[i];
return(dtemp);
#endif
#ifdef UNROLL
m = n % 5;
if (m != 0) {
for (i = 0; i < m; i++)
dtemp = dtemp + dx[i]*dy[i];
if (n < 5) return(dtemp);
}
for (i = m; i < n; i = i + 5) {
dtemp = dtemp + dx[i]*dy[i] +
dx[i+1]*dy[i+1] + dx[i+2]*dy[i+2] +
dx[i+3]*dy[i+3] + dx[i+4]*dy[i+4];
}
return(dtemp);
#endif
}
/*----------------------*/
void dscal(int n, REAL da, REAL dx[], int incx)
/* scales a vector by a constant.
jack dongarra, linpack, 3/11/78.
*/
{
int i,m,mp1,nincx;
mp1 = 0;
m = 0;
if(n <= 0)return;
if(incx != 1) {
/* code for increment not equal to 1 */
nincx = n*incx;
for (i = 0; i < nincx; i = i + incx)
dx[i] = da*dx[i];
return;
}
/* code for increment equal to 1 */
#ifdef ROLL
for (i = 0; i < n; i++)
dx[i] = da*dx[i];
#endif
#ifdef UNROLL
m = n % 5;
if (m != 0) {
for (i = 0; i < m; i++)
dx[i] = da*dx[i];
if (n < 5) return;
}
for (i = m; i < n; i = i + 5){
dx[i] = da*dx[i];
dx[i+1] = da*dx[i+1];
dx[i+2] = da*dx[i+2];
dx[i+3] = da*dx[i+3];
dx[i+4] = da*dx[i+4];
}
#endif
}
/*----------------------*/
int idamax(int n, REAL dx[], int incx)
/*
finds the index of element having max. absolute value.
jack dongarra, linpack, 3/11/78.
*/
{
REAL dmax;
int i, ix, itemp;
if( n < 1 ) return(-1);
if(n ==1 ) return(0);
if(incx != 1) {
/* code for increment not equal to 1 */
ix = 1;
dmax = fabs((double)dx[0]);
ix = ix + incx;
for (i = 1; i < n; i++) {
if(fabs((double)dx[ix]) > dmax) {
itemp = i;
dmax = fabs((double)dx[ix]);
}
ix = ix + incx;
}
}
else {
/* code for increment equal to 1 */
itemp = 0;
dmax = fabs((double)dx[0]);
for (i = 1; i < n; i++) {
if(fabs((double)dx[i]) > dmax) {
itemp = i;
dmax = fabs((double)dx[i]);
}
}
}
return (itemp);
}
/*----------------------*/
REAL epslon (REAL x)
/*
estimate unit roundoff in quantities of size x.
*/
{
REAL a,b,c,eps;
/*
this program should function properly on all systems
satisfying the following two assumptions,
1. the base used in representing dfloating point
numbers is not a power of three.
2. the quantity a in statement 10 is represented to
the accuracy used in dfloating point variables
that are stored in memory.
the statement number 10 and the go to 10 are intended to
force optimizing compilers to generate code satisfying
assumption 2.
under these assumptions, it should be true that,
a is not exactly equal to four-thirds,
b has a zero for its last bit or digit,
c is not exactly equal to one,
eps measures the separation of 1.0 from
the next larger dfloating point number.
the developers of eispack would appreciate being informed
about any systems where these assumptions do not hold.
*****************************************************************
this routine is one of the auxiliary routines used by eispack iii
to avoid machine dependencies.
*****************************************************************
this version dated 4/6/83.
*/
a = 4.0e0/3.0e0;
eps = ZERO;
while (eps == ZERO) {
b = a - ONE;
c = b + b + b;
eps = fabs((double)(c-ONE));
}
return(eps*fabs((double)x));
}
/*----------------------*/
void dmxpy (int n1, REAL y[], int n2, int ldm, REAL x[], REAL m[])
/* We would like to declare m[][ldm], but c does not allow it. In this
function, references to m[i][j] are written m[ldm*i+j]. */
/*
purpose:
multiply matrix m times vector x and add the result to vector y.
parameters:
n1 integer, number of elements in vector y, and number of rows in
matrix m
y double [n1], vector of length n1 to which is added
the product m*x
n2 integer, number of elements in vector x, and number of columns
in matrix m
ldm integer, leading dimension of array m
x double [n2], vector of length n2
m double [ldm][n2], matrix of n1 rows and n2 columns
----------------------------------------------------------------------
*/
{
int j,i,jmin;
/* cleanup odd vector */
j = n2 % 2;
if (j >= 1) {
j = j - 1;
for (i = 0; i < n1; i++)
y[i] = (y[i]) + x[j]*m[ldm*j+i];
}
/* cleanup odd group of two vectors */
j = n2 % 4;
if (j >= 2) {
j = j - 1;
for (i = 0; i < n1; i++)
y[i] = ( (y[i])
+ x[j-1]*m[ldm*(j-1)+i]) + x[j]*m[ldm*j+i];
}
/* cleanup odd group of four vectors */
j = n2 % 8;
if (j >= 4) {
j = j - 1;
for (i = 0; i < n1; i++)
y[i] = ((( (y[i])
+ x[j-3]*m[ldm*(j-3)+i])
+ x[j-2]*m[ldm*(j-2)+i])
+ x[j-1]*m[ldm*(j-1)+i]) + x[j]*m[ldm*j+i];
}
/* cleanup odd group of eight vectors */
j = n2 % 16;
if (j >= 8) {
j = j - 1;
for (i = 0; i < n1; i++)
y[i] = ((((((( (y[i])
+ x[j-7]*m[ldm*(j-7)+i]) + x[j-6]*m[ldm*(j-6)+i])
+ x[j-5]*m[ldm*(j-5)+i]) + x[j-4]*m[ldm*(j-4)+i])
+ x[j-3]*m[ldm*(j-3)+i]) + x[j-2]*m[ldm*(j-2)+i])
+ x[j-1]*m[ldm*(j-1)+i]) + x[j] *m[ldm*j+i];
}
/* main loop - groups of sixteen vectors */
jmin = (n2%16)+16;
for (j = jmin-1; j < n2; j = j + 16) {
for (i = 0; i < n1; i++)
y[i] = ((((((((((((((( (y[i])
+ x[j-15]*m[ldm*(j-15)+i])
+ x[j-14]*m[ldm*(j-14)+i])
+ x[j-13]*m[ldm*(j-13)+i])
+ x[j-12]*m[ldm*(j-12)+i])
+ x[j-11]*m[ldm*(j-11)+i])
+ x[j-10]*m[ldm*(j-10)+i])
+ x[j- 9]*m[ldm*(j- 9)+i])
+ x[j- 8]*m[ldm*(j- 8)+i])
+ x[j- 7]*m[ldm*(j- 7)+i])
+ x[j- 6]*m[ldm*(j- 6)+i])
+ x[j- 5]*m[ldm*(j- 5)+i])
+ x[j- 4]*m[ldm*(j- 4)+i])
+ x[j- 3]*m[ldm*(j- 3)+i])
+ x[j- 2]*m[ldm*(j- 2)+i])
+ x[j- 1]*m[ldm*(j- 1)+i])
+ x[j] *m[ldm*j+i];
}
return;
}