6.5.5 vsip_dqrsol_p - Solve Linear Systems Using QR Decomposition

typedef enum _vsip_qrd_prob { 
  VSIP_COV = 0, /* Solve a covariance linear system problem */ 
  VSIP_LLS = 1  /* Solve a linear least squares problem */ 
} vsip_qrd_prob; 
 
int vsip_qrsol_f(const vsip_qr_f *qrd, vsip_qrd_prob prob, const vsip_mview_f *xb); 
int vsip_qrsol_d(const vsip_qr_d *qrd, vsip_qrd_prob prob, const vsip_mview_d *xb); 
int vsip_cqrsol_f(const vsip_cqr_f *qrd, vsip_qrd_prob prob, const vsip_cmview_f *xb); 
int vsip_cqrsol_d(const vsip_cqr_d *qrd, vsip_qrd_prob prob, const vsip_cmview_d *xb);

Description

This function solves linear systems of equations using a previously computed QR decomposition for a matrix with with rank . It can solve a covariance linear system problem

for real or

for complex. Or a linear least squares problem,

Parameters

• const vsip_dqr_p* qrd: Pointer to the QR decomposition object containing a previously computed decomposition.

• vsip_qrd_prob prob: Type of problem to solve.

• const vsip_dmview_p* xb: On input, contains the right-hand side matrix of size for a covariance problem and for a least squares problem. On output, contains the solution .

Return Value

• Returns 0 on success.

• Returns a non-zero value on error

Notes

• The QR decomposition must have been previously computed using vsip_dqrd_p .

• The QR object must have been created with an option that saves the matrix to use this function.