MB_DTRSV – Solves one of the system of equations A*x = b or A^T*x = b for triangular matrix A

Block SymbolLicensing group: STANDARD
PIC

Function Description
The output references yA and yX are always set to the corresponding input references uA and uX. If HLD = on then nothing is computed otherwise the BLAS function DTRSV is called internally:

DTRSV(sLUPLO, sTRANS, sNDIAG, N, uA, LDA, uX, INCX);

where parameters of DTRSV are set in the following way:

  • If LUPLO = on then the string sLUPLO is set to "L" else it is set to "U".
  • Integer input trans is mapped to the string sTRANS: {0,1}"N", {2}"T" and {3}"C".
  • If NDIAG = on then the string sNDIAG is set to "N" else it is set to "U".
  • N is number of rows and columns of the square matrix referenced by uA.
  • LDA is the leading dimension of matrix referenced by uA.
  • If the input incx0 then INCX is set to incx else INCX is set to 1.

The error flag E is set to on if:

  • the reference uA or uX is not defined (i.e. input uA or uX is not connected),
  • trans is less than 0 or greater than 3,
  • matrix referenced by uA is not square,
  • (N 1) |INCX| + 1 > CNTX, where CNTX is a number of the vector or matrix elements referenced by uX.
  • the call of the function DTRMV returns error using the function XERBLA, see the system log.

See BLAS documentation [7] for more details.

Inputs

uA

Input reference to matrix A

Reference

uX

Input reference to vector x

Reference

LUPLO

Matrix A is a lower triangular matrix

Bool

trans

Transposition of the input matrix   0  3

Long (I32)

NDIAG

Matrix A is not assumed to be unit triangular

Bool

incx

Index increment of vector x

Long (I32)

HLD

Hold

Bool

Outputs

yA

Output reference to matrix A

Reference

yX

Output reference to vector x

Reference

E

Error indicator

Bool

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