NAME

SYNOPSIS

  SUBROUTINE SCHDD( A, LDA, N, X, Z, LDZ, NZ, Y, RHO, COS, SIN, INFO)
  INTEGER LDA, N, LDZ, NZ, INFO
  REAL A(LDA,*), X(*), Z(LDZ,*), Y(*), RHO(*), COS(*), SIN(*)
 
  SUBROUTINE SCHDD_64( A, LDA, N, X, Z, LDZ, NZ, Y, RHO, COS, SIN, 
 *      INFO)
  INTEGER*8 LDA, N, LDZ, NZ, INFO
  REAL A(LDA,*), X(*), Z(LDZ,*), Y(*), RHO(*), COS(*), SIN(*)
 

C INTERFACE

void schdd(float *a, int lda, int n, float *x, float *z, int ldz, int nz, float *y, float *rho, float *cos, float *sin, int *info);

void schdd_64(float *a, long lda, long n, float *x, float *z, long ldz, long nz, float *y, float *rho, float *cos, float *sin, long *info);

ARGUMENTS

* A (input/output)

On entry, the upper triangular matrix A. On exit, A has been downdated. The strict lower triangle of A is not referenced.

* LDA (input)

Leading dimension of the array A as specified in a dimension or type statement. LDA >= max(1,N).

* N (input)

Order of the matrix A. N >= 0.

* X (input)

Row to be added to A.

* Z (input/output)

Vectors to be downdated with A.

* LDZ (input)

Leading dimension on the array Z as specified in a dimension or type statement. LDZ >= max(1,N).

* NZ (input)

Number of vectors to be downdated with A. NZ >= 0. If NZ = 0 then Z, Y, and RHO are not used.

* Y (input)

Scalars for downdating the vectors in Z.

* RHO (input/output)

On entry, the norms of the residual vectors that are to be downdated. On exit, RHO has been downdated. If RHO(i) is negative on entry then it is not changed.

* COS (input/output)

Cosines of the transforming rotations.

* SIN (output)

Sines of the transforming rotations.

* INFO (output)

On exit:

INFO = 0 Subroutine completed normally.

INFO = -1 A could not be downdated; all values are left unchanged.

INFO = 1 Some RHOs could not be downdated; all RHOs that could not be downdated are changed to -1.