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Annotation of capa/capa51/pProj/linpack.c, revision 1.1.1.1

1.1       albertel    1: #include <math.h>
                      2: float sdot(long n,float *sx,long incx,float *sy,long incy)
                      3: {
                      4: static long i,ix,iy,m,mp1;
                      5: static float sdot,stemp;
                      6:     stemp = sdot = 0.0;
                      7:     if(n <= 0) return sdot;
                      8:     if(incx == 1 && incy == 1) goto S20;
                      9:     ix = iy = 1;
                     10:     if(incx < 0) ix = (-n+1)*incx+1;
                     11:     if(incy < 0) iy = (-n+1)*incy+1;
                     12:     for(i=1; i<=n; i++) {
                     13:         stemp += (*(sx+ix-1)**(sy+iy-1));
                     14:         ix += incx;
                     15:         iy += incy;
                     16:     }
                     17:     sdot = stemp;
                     18:     return sdot;
                     19: S20:
                     20:     m = n % 5L;
                     21:     if(m == 0) goto S40;
                     22:     for(i=0; i<m; i++) stemp += (*(sx+i)**(sy+i));
                     23:     if(n < 5) goto S60;
                     24: S40:
                     25:     mp1 = m+1;
                     26:     for(i=mp1; i<=n; i+=5) stemp += (*(sx+i-1)**(sy+i-1)+*(sx+i)**(sy+i)+*(sx+i
                     27:       +1)**(sy+i+1)+*(sx+i+2)**(sy+i+2)+*(sx+i+3)**(sy+i+3));
                     28: S60:
                     29:     sdot = stemp;
                     30:     return sdot;
                     31: }
                     32: void spofa(float *a,long lda,long n,long *info)
                     33: /*
                     34:      SPOFA FACTORS A REAL SYMMETRIC POSITIVE DEFINITE MATRIX.
                     35:      SPOFA IS USUALLY CALLED BY SPOCO, BUT IT CAN BE CALLED
                     36:      DIRECTLY WITH A SAVING IN TIME IF  RCOND  IS NOT NEEDED.
                     37:      (TIME FOR SPOCO) = (1 + 18/N)*(TIME FOR SPOFA) .
                     38:      ON ENTRY
                     39:         A       REAL(LDA, N)
                     40:                 THE SYMMETRIC MATRIX TO BE FACTORED.  ONLY THE
                     41:                 DIAGONAL AND UPPER TRIANGLE ARE USED.
                     42:         LDA     INTEGER
                     43:                 THE LEADING DIMENSION OF THE ARRAY  A .
                     44:         N       INTEGER
                     45:                 THE ORDER OF THE MATRIX  A .
                     46:      ON RETURN
                     47:         A       AN UPPER TRIANGULAR MATRIX  R  SO THAT  A = TRANS(R)*R
                     48:                 WHERE  TRANS(R)  IS THE TRANSPOSE.
                     49:                 THE STRICT LOWER TRIANGLE IS UNALTERED.
                     50:                 IF  INFO .NE. 0 , THE FACTORIZATION IS NOT COMPLETE.
                     51:         INFO    INTEGER
                     52:                 = 0  FOR NORMAL RETURN.
                     53:                 = K  SIGNALS AN ERROR CONDITION.  THE LEADING MINOR
                     54:                      OF ORDER  K  IS NOT POSITIVE DEFINITE.
                     55:      LINPACK.  THIS VERSION DATED 08/14/78 .
                     56:      CLEVE MOLER, UNIVERSITY OF NEW MEXICO, ARGONNE NATIONAL LAB.
                     57:      SUBROUTINES AND FUNCTIONS
                     58:      BLAS SDOT
                     59:      FORTRAN SQRT
                     60:      INTERNAL VARIABLES
                     61: */
                     62: {
                     63: extern float sdot(long n,float *sx,long incx,float *sy,long incy);
                     64: static long j,jm1,k;
                     65: static float t,s;
                     66: /*
                     67:      BEGIN BLOCK WITH ...EXITS TO 40
                     68: */
                     69:     for(j=1; j<=n; j++) {
                     70:         *info = j;
                     71:         s = 0.0;
                     72:         jm1 = j-1;
                     73:         if(jm1 < 1) goto S20;
                     74:         for(k=0; k<jm1; k++) {
                     75:             t = *(a+k+(j-1)*lda)-sdot(k,(a+k*lda),1L,(a+(j-1)*lda),1L);
                     76:             t /=  *(a+k+k*lda);
                     77:             *(a+k+(j-1)*lda) = t;
                     78:             s += (t*t);
                     79:         }
                     80: S20:
                     81:         s = *(a+j-1+(j-1)*lda)-s;
                     82: /*
                     83:      ......EXIT
                     84: */
                     85:         if(s <= 0.0) goto S40;
                     86:         *(a+j-1+(j-1)*lda) = sqrt(s);
                     87:     }
                     88:     *info = 0;
                     89: S40:
                     90:     return;
                     91: }