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*> \brief <b> CPTSVX computes the solution to system of linear equations A * X = B for PT matrices</b>** =========== DOCUMENTATION ===========** Online html documentation available at * http://www.netlib.org/lapack/explore-html/ **> \htmlonly*> Download CPTSVX + dependencies *> <a href="http://www.netlib.org/cgi-bin/netlibfiles.tgz?format=tgz&filename=/lapack/lapack_routine/cptsvx.f"> *> [TGZ]</a> *> <a href="http://www.netlib.org/cgi-bin/netlibfiles.zip?format=zip&filename=/lapack/lapack_routine/cptsvx.f"> *> [ZIP]</a> *> <a href="http://www.netlib.org/cgi-bin/netlibfiles.txt?format=txt&filename=/lapack/lapack_routine/cptsvx.f"> *> [TXT]</a>*> \endhtmlonly ** Definition:* ===========** SUBROUTINE CPTSVX( FACT, N, NRHS, D, E, DF, EF, B, LDB, X, LDX,* RCOND, FERR, BERR, WORK, RWORK, INFO )* * .. Scalar Arguments ..* CHARACTER FACT* INTEGER INFO, LDB, LDX, N, NRHS* REAL RCOND* ..* .. Array Arguments ..* REAL BERR( * ), D( * ), DF( * ), FERR( * ),* $ RWORK( * )* COMPLEX B( LDB, * ), E( * ), EF( * ), WORK( * ),* $ X( LDX, * )* ..* **> \par Purpose:* =============*>*> \verbatim*>*> CPTSVX uses the factorization A = L*D*L**H to compute the solution*> to a complex system of linear equations A*X = B, where A is an*> N-by-N Hermitian positive definite tridiagonal matrix and X and B*> are N-by-NRHS matrices.*>*> Error bounds on the solution and a condition estimate are also*> provided.*> \endverbatim**> \par Description:* =================*>*> \verbatim*>*> The following steps are performed:*>*> 1. If FACT = 'N', the matrix A is factored as A = L*D*L**H, where L*> is a unit lower bidiagonal matrix and D is diagonal. The*> factorization can also be regarded as having the form*> A = U**H*D*U.*>*> 2. If the leading i-by-i principal minor is not positive definite,