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<HEAD><TITLE>MB01OO - SLICOT Library Routine Documentation</TITLE>
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<H2><A Name="MB01OO">MB01OO</A></H2>
<H3>
Computation of P or P' with P = op(H) X op(E)' with X symmetric, H upper Hessenberg, and E upper triangular
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<A HREF ="#Specification"><B>[Specification]</B></A>
<A HREF ="#Arguments"><B>[Arguments]</B></A>
<A HREF ="#Method"><B>[Method]</B></A>
<A HREF ="#References"><B>[References]</B></A>
<A HREF ="#Comments"><B>[Comments]</B></A>
<A HREF ="#Example"><B>[Example]</B></A>
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<B><FONT SIZE="+1">Purpose</FONT></B>
<PRE>
To compute either P or P', with P defined by the matrix formula
P = op( H )*X*op( E )',
where H is an upper Hessenberg matrix, X is a symmetric matrix,
E is an upper triangular matrix, and op( M ) is one of
op( M ) = M or op( M ) = M'.
</PRE>
<A name="Specification"><B><FONT SIZE="+1">Specification</FONT></B></A>
<PRE>
SUBROUTINE MB01OO( UPLO, TRANS, N, H, LDH, X, LDX, E, LDE, P, LDP,
$ INFO )
C .. Scalar Arguments ..
INTEGER INFO, LDE, LDH, LDP, LDX, N
CHARACTER TRANS, UPLO
C .. Array Arguments ..
DOUBLE PRECISION E(LDE,*), H(LDH,*), P(LDP,*), X(LDX,*)
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<A name="Arguments"><B><FONT SIZE="+1">Arguments</FONT></B></A>
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<B>Mode Parameters</B>
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UPLO CHARACTER*1
Specifies which triangle of the symmetric matrix X is
given as follows:
= 'U': the upper triangular part is given;
= 'L': the lower triangular part is given.
TRANS CHARACTER*1
Specifies the operation to be performed as follows:
= 'N': compute P = H*X*E';
= 'T' or 'C': compute P' = E'*X*H.
</PRE>
<B>Input/Output Parameters</B>
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N (input) INTEGER
The order of the matrices H, X, E, and P. N >= 0.
H (input) DOUBLE PRECISION array, dimension (LDH,N)
On entry, the leading N-by-N upper Hessenberg part of this
array must contain the upper Hessenberg matrix H.
The remaining part of this array is not referenced.
LDH INTEGER
The leading dimension of the array H. LDH >= MAX(1,N).
X (input) DOUBLE PRECISION array, dimension (LDX,N)
On entry, if UPLO = 'U', the leading N-by-N upper
triangular part of this array must contain the upper
triangular part of the symmetric matrix X and the strictly
lower triangular part of the array is not referenced.
On entry, if UPLO = 'L', the leading N-by-N lower
triangular part of this array must contain the lower
triangular part of the symmetric matrix X and the strictly
upper triangular part of the array is not referenced.
LDX INTEGER
The leading dimension of the array X. LDX >= MAX(1,N).
E (input) DOUBLE PRECISION array, dimension (LDE,N)
On entry, the leading N-by-N upper triangular part of this
array must contain the upper triangular matrix E.
The remaining part of this array is not referenced.
LDE INTEGER
The leading dimension of array E. LDE >= MAX(1,N).
P (output) DOUBLE PRECISION array, dimension (LDP,N)
On exit, the leading N-by-N part of this array contains
the computed matrix P = H*X*E', if TRANS = 'N', or
the computed matrix P' = E'*X*H, if TRANS = 'T'.
LDP INTEGER
The leading dimension of the array P. LDP >= MAX(1,N).
</PRE>
<B>Error Indicator</B>
<PRE>
INFO INTEGER
= 0: successful exit;
< 0: if INFO = -k, the k-th argument had an illegal
value.
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<A name="Method"><B><FONT SIZE="+1">Method</FONT></B></A>
<PRE>
The matrix expression is efficiently evaluated taking the
structure into account, and using BLAS and SLICOT routines.
Let W = H*X, or W = X*H, computed using SLICOT Library routine
MB01OS. The result is then obtained calling BLAS 3 routine DTRMM.
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<A name="Numerical Aspects"><B><FONT SIZE="+1">Numerical Aspects</FONT></B></A>
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The algorithm requires approximately N**3 operations.
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<A name="Comments"><B><FONT SIZE="+1">Further Comments</FONT></B></A>
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None
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<A name="Example"><B><FONT SIZE="+1">Example</FONT></B></A>
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<B>Program Text</B>
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None
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<B>Program Data</B>
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None
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<B>Program Results</B>
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None
</PRE>
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