?ptts2

Interface Definition

C interface:

void sptts2_(const int *N, const int *NRHS, float *D, float *E, float *B, const int *LDB);

void dptts2_(const int *N, const int *NRHS, double *D, double *E, double *B, const int *LDB);

void cptts2_(const int *IUPLO, const int *N, const int *NRHS, float *D, float _Complex *E, float _Complex *B, const int *LDB);

void zptts2_(const int *IUPLO, const int *N, const int *NRHS, double *D, double _Complex *E, double _Complex *B, const int *LDB);

Fortran interface:

SPTTS2(N, NRHS, D, E, B, LDB);

DPTTS2(N, NRHS, D, E, B, LDB);

CPTTS2(IUPLO, N, NRHS, D, E, B, LDB);

ZPTTS2(IUPLO, N, NRHS, D, E, B, LDB);

Parameters

Parameter	Type	Description	Input/Output
IUPLO (specific to complex numbers)	Integer	1: A=U*HDU 0: A=LDL*H	Input
N	Integer	Number of dimensions of matrix A, N ≥ 0.	Input
NRHS	Integer	Number of columns in matrix B, NRHS ≥ 0.	Input
D	For sptts2/cptts2, D is a single-precision floating-point array. For dptts2/zptts2, D is a double-precision floating-point array.	Diagonal element of tridiagonal matrix A, with a dimension of N.	Input
E	A single-precision floating-point array for sptts2 A double-precision floating-point array for dptts2 A single-precision complex array for cptts2 A double-precision complex array for zptts2	Sub-diagonal element of tridiagonal matrix A, with a dimension of N-1.	Input
B	A single-precision floating-point array for sptts2 A double-precision floating-point array for dptts2 A single-precision complex array for cptts2 A double-precision complex array for zptts2	When as an input value, it is a right-hand side matrix, and the dimension is (LDB, NRHS). When as an output value, it is the result X, and the dimension is (LDB, NRHS).	Input, output
LDB	Integer	Leading dimension of matrix B.	Input

Dependency

#include "klapack.h"

Examples

C interface:

    const int n = 4;
    const int ldb = n;
    const int nrhs = 1;
    double d[] = {7.608696,7.739130, 7.347826,4.652174};
    double e[] = {0.352941,0.000000,0.823529};
    double b[] = {0.300000,0.100000,0.700000,0.200000};
    
    dptts2_(&n, &nrhs, d, e, b, &ldb);
/* 
* Output: 
*   b: 0.039697        -0.000760       0.161909        -0.080924
*/

Fortran interface:

PARAMETER (n = 4) 
PARAMETER (ldb = 4)
PARAMETER (nrhs = 1) 
REAL(8) :: d(n) 
REAL(8) :: e(n-1)
REAL(8) :: b(ldb, nrhs)  
  
DATA d / 7.608696,7.739130, 7.347826,4.652174 / 
DATA e / 0.352941,0.000000,0.823529 /
DATA b / 0.300000,0.100000,0.700000,0.200000 /
 EXTERNAL DPTTS2 
 CALL DPTTS2(n, nrhs, d, e, b, ldb);
* 
* Output: 
*  b: 0.039697        -0.000760       0.161909        -0.080924

Parent topic: Back Substitution Solution Functions