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---
:name: strsyl
:md5sum: 650bfc17167d0bb5e57a982981f61818
:category: :subroutine
:arguments:
- trana:
:type: char
:intent: input
- tranb:
:type: char
:intent: input
- isgn:
:type: integer
:intent: input
- m:
:type: integer
:intent: input
- n:
:type: integer
:intent: input
- a:
:type: real
:intent: input
:dims:
- lda
- m
- lda:
:type: integer
:intent: input
- b:
:type: real
:intent: input
:dims:
- ldb
- n
- ldb:
:type: integer
:intent: input
- c:
:type: real
:intent: input/output
:dims:
- ldc
- n
- ldc:
:type: integer
:intent: input
- scale:
:type: real
:intent: output
- info:
:type: integer
:intent: output
:substitutions: {}
:fortran_help: " SUBROUTINE STRSYL( TRANA, TRANB, ISGN, M, N, A, LDA, B, LDB, C, LDC, SCALE, INFO )\n\n\
* Purpose\n\
* =======\n\
*\n\
* STRSYL solves the real Sylvester matrix equation:\n\
*\n\
* op(A)*X + X*op(B) = scale*C or\n\
* op(A)*X - X*op(B) = scale*C,\n\
*\n\
* where op(A) = A or A**T, and A and B are both upper quasi-\n\
* triangular. A is M-by-M and B is N-by-N; the right hand side C and\n\
* the solution X are M-by-N; and scale is an output scale factor, set\n\
* <= 1 to avoid overflow in X.\n\
*\n\
* A and B must be in Schur canonical form (as returned by SHSEQR), that\n\
* is, block upper triangular with 1-by-1 and 2-by-2 diagonal blocks;\n\
* each 2-by-2 diagonal block has its diagonal elements equal and its\n\
* off-diagonal elements of opposite sign.\n\
*\n\n\
* Arguments\n\
* =========\n\
*\n\
* TRANA (input) CHARACTER*1\n\
* Specifies the option op(A):\n\
* = 'N': op(A) = A (No transpose)\n\
* = 'T': op(A) = A**T (Transpose)\n\
* = 'C': op(A) = A**H (Conjugate transpose = Transpose)\n\
*\n\
* TRANB (input) CHARACTER*1\n\
* Specifies the option op(B):\n\
* = 'N': op(B) = B (No transpose)\n\
* = 'T': op(B) = B**T (Transpose)\n\
* = 'C': op(B) = B**H (Conjugate transpose = Transpose)\n\
*\n\
* ISGN (input) INTEGER\n\
* Specifies the sign in the equation:\n\
* = +1: solve op(A)*X + X*op(B) = scale*C\n\
* = -1: solve op(A)*X - X*op(B) = scale*C\n\
*\n\
* M (input) INTEGER\n\
* The order of the matrix A, and the number of rows in the\n\
* matrices X and C. M >= 0.\n\
*\n\
* N (input) INTEGER\n\
* The order of the matrix B, and the number of columns in the\n\
* matrices X and C. N >= 0.\n\
*\n\
* A (input) REAL array, dimension (LDA,M)\n\
* The upper quasi-triangular matrix A, in Schur canonical form.\n\
*\n\
* LDA (input) INTEGER\n\
* The leading dimension of the array A. LDA >= max(1,M).\n\
*\n\
* B (input) REAL array, dimension (LDB,N)\n\
* The upper quasi-triangular matrix B, in Schur canonical form.\n\
*\n\
* LDB (input) INTEGER\n\
* The leading dimension of the array B. LDB >= max(1,N).\n\
*\n\
* C (input/output) REAL array, dimension (LDC,N)\n\
* On entry, the M-by-N right hand side matrix C.\n\
* On exit, C is overwritten by the solution matrix X.\n\
*\n\
* LDC (input) INTEGER\n\
* The leading dimension of the array C. LDC >= max(1,M)\n\
*\n\
* SCALE (output) REAL\n\
* The scale factor, scale, set <= 1 to avoid overflow in X.\n\
*\n\
* INFO (output) INTEGER\n\
* = 0: successful exit\n\
* < 0: if INFO = -i, the i-th argument had an illegal value\n\
* = 1: A and B have common or very close eigenvalues; perturbed\n\
* values were used to solve the equation (but the matrices\n\
* A and B are unchanged).\n\
*\n\n\
* =====================================================================\n\
*\n"
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