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

MB_DTRSV – Solves one of the system of equations Ax = b or A^Tx = b for triangular matrix A

Block SymbolLicensing group: STANDARD

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: ${0, 1} \to "N"$ , ${2} \to "T"$ and ${3} \to "C"$ .
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 $incx \neq 0$ 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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