dlaisnan.f(3) LAPACK dlaisnan.f(3)NAME
dlaisnan.f -
SYNOPSIS
Functions/Subroutines
LOGICAL function dlaisnan (DIN1, DIN2)
DLAISNAN tests input for NaN by comparing two arguments for inequality.
Function/Subroutine Documentation
LOGICAL function dlaisnan (double precisionDIN1, double precisionDIN2)
DLAISNAN tests input for NaN by comparing two arguments for inequality.
Purpose:
This routine is not for general use. It exists solely to avoid
over-optimization in DISNAN.
DLAISNAN checks for NaNs by comparing its two arguments for
inequality. NaN is the only floating-point value where NaN != NaN
returns .TRUE. To check for NaNs, pass the same variable as both
arguments.
A compiler must assume that the two arguments are
not the same variable, and the test will not be optimized away.
Interprocedural or whole-program optimization may delete this
test. The ISNAN functions will be replaced by the correct
Fortran 03 intrinsic once the intrinsic is widely available.
Parameters:
DIN1
DIN1 is DOUBLE PRECISION
DIN2
DIN2 is DOUBLE PRECISION
Two numbers to compare for inequality.
Author:
Univ. of Tennessee
Univ. of California Berkeley
Univ. of Colorado Denver
NAG Ltd.
Date:
September 2012
Definition at line 75 of file dlaisnan.f.
Author
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Version 3.4.2 Tue Sep 25 2012 dlaisnan.f(3)
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dlags2.f(3) LAPACK dlags2.f(3)NAME
dlags2.f -
SYNOPSIS
Functions/Subroutines
subroutine dlags2 (UPPER, A1, A2, A3, B1, B2, B3, CSU, SNU, CSV, SNV, CSQ, SNQ)
DLAGS2 computes 2-by-2 orthogonal matrices U, V, and Q, and applies them to matrices A and B such that the rows of the transformed A
and B are parallel.
Function/Subroutine Documentation
subroutine dlags2 (logicalUPPER, double precisionA1, double precisionA2, double precisionA3, double precisionB1, double precisionB2, double
precisionB3, double precisionCSU, double precisionSNU, double precisionCSV, double precisionSNV, double precisionCSQ, double precisionSNQ)
DLAGS2 computes 2-by-2 orthogonal matrices U, V, and Q, and applies them to matrices A and B such that the rows of the transformed A and B
are parallel.
Purpose:
DLAGS2 computes 2-by-2 orthogonal matrices U, V and Q, such
that if ( UPPER ) then
U**T *A*Q = U**T *( A1 A2 )*Q = ( x 0 )
( 0 A3 ) ( x x )
and
V**T*B*Q = V**T *( B1 B2 )*Q = ( x 0 )
( 0 B3 ) ( x x )
or if ( .NOT.UPPER ) then
U**T *A*Q = U**T *( A1 0 )*Q = ( x x )
( A2 A3 ) ( 0 x )
and
V**T*B*Q = V**T*( B1 0 )*Q = ( x x )
( B2 B3 ) ( 0 x )
The rows of the transformed A and B are parallel, where
U = ( CSU SNU ), V = ( CSV SNV ), Q = ( CSQ SNQ )
( -SNU CSU ) ( -SNV CSV ) ( -SNQ CSQ )
Z**T denotes the transpose of Z.
Parameters:
UPPER
UPPER is LOGICAL
= .TRUE.: the input matrices A and B are upper triangular.
= .FALSE.: the input matrices A and B are lower triangular.
A1
A1 is DOUBLE PRECISION
A2
A2 is DOUBLE PRECISION
A3
A3 is DOUBLE PRECISION
On entry, A1, A2 and A3 are elements of the input 2-by-2
upper (lower) triangular matrix A.
B1
B1 is DOUBLE PRECISION
B2
B2 is DOUBLE PRECISION
B3
B3 is DOUBLE PRECISION
On entry, B1, B2 and B3 are elements of the input 2-by-2
upper (lower) triangular matrix B.
CSU
CSU is DOUBLE PRECISION
SNU
SNU is DOUBLE PRECISION
The desired orthogonal matrix U.
CSV
CSV is DOUBLE PRECISION
SNV
SNV is DOUBLE PRECISION
The desired orthogonal matrix V.
CSQ
CSQ is DOUBLE PRECISION
SNQ
SNQ is DOUBLE PRECISION
The desired orthogonal matrix Q.
Author:
Univ. of Tennessee
Univ. of California Berkeley
Univ. of Colorado Denver
NAG Ltd.
Date:
September 2012
Definition at line 152 of file dlags2.f.
Author
Generated automatically by Doxygen for LAPACK from the source code.
Version 3.4.2 Tue Sep 25 2012 dlags2.f(3)