Category : C Source Code
Archive   : CEPHES22.ZIP
Filename : EIGTST.C

 
Output of file : EIGTST.C contained in archive : CEPHES22.ZIP
/* Test program for eigens.c
*/

#define N 11
#define DEBUG 0
static double A[N*N], A0[N*N], X[N*N], D[N*N];
static double RR[N*N];
static double B[N], Y[N];
static int IPS[N];
double maxoffd(), sqrt();

main()
{
long ntrials;
int i, j, k;
double x, e, merr;

merr = 0.0;
ntrials = 0;

loop:

/* Fill A[] with random numbers */
k = N*(N+1)/2;
for( i=0; i {
drand( &x );
x -= 1.5;
x = x + x;
A[i] = x;
}
/* Unpack A into a symmetric matrix A0 */
tritosquare( N, A, A0 );

eigens( A, RR, B, N );
mtransp( N, RR, RR );

#if DEBUG
/* Print the computed eigenvalues */
for( i=0; i printf( "%6.2f", B[i] );
/* Print the reduced triangular matrix */
printf( "\n" );
k = 0;
for( i=0; i {
for( j=0; j<=i; j++ )
{
printf( "%6.2f", A[k] );
k += 1;
}
printf( "\n" );
}

/* Print the original symmetric matrix */
printf( "\n" );
for( i=0; i {
for( j=0; j printf( "%6.2f", A0[N*i+j] );
printf( "\n" );
}

/* Print the matrix of eigenvectors */
printf( "\n" );
for( i=0; i {
for( j=0; j printf( "%6.2f", RR[N*i+j] );
printf( "\n" );
}

#endif

/* Multiply the original matrix by the eigenvectors */
mmmpy( N, N, A0, RR, D );
/* Divide each result vector by the corresponding eigenvalue. */
k = 0;
for( i=0; i {
x = B[i];
for( j=0; j {
D[k] /= x;
k += 1;
}
}

#if DEBUG
printf( "\n" );
for( i=0; i {
for( j=0; j printf( "%6.2f", D[N*i+j] );
printf( "\n" );
}
#endif

/* Compare the result with the computed eigenvector */
mtransp( N, D, D );
e = 0.0;
for( i=0; i {
x = D[i] - RR[i];
if( x < 0 )
x = -x;
if( x > e )
e = x;
}
if( e > merr )
merr = e;
ntrials += 1;
printf( "%4ld %.3e\n", ntrials, merr );
goto loop;
}


  3 Responses to “Category : C Source Code
Archive   : CEPHES22.ZIP
Filename : EIGTST.C
”

  1. Daniel says:
    January 27, 2013 at 3:59 pm

    Very nice! Thank you for this wonderful archive. I wonder why I found it only now. Long live the BBS file archives!

  2. Joshie says:
    March 18, 2014 at 4:57 pm

    This is so awesome! 😀 I’d be cool if you could download an entire archive of this at once, though.

  3. DiskingRound says:
    January 14, 2015 at 10:57 pm

    But one thing that puzzles me is the “mtswslnkmcjklsdlsbdmMICROSOFT” string. There is an article about it here. It is definitely worth a read: http://www.os2museum.com/wp/mtswslnk/