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NAME DPTTRS - solve a system of linear equations A * X = B with a symmetric positive definite tridiagonal matrix A using the factorization A = L*D*L**T or A = U**T*D*U computed by DPTTRF SYNOPSIS SUBROUTINE DPTTRS( N, NRHS, D, E, B, LDB, INFO ) INTEGER INFO, LDB, N, NRHS DOUBLE PRECISION B( LDB, * ), D( * ), E( * ) PURPOSE DPTTRS solves a system of linear equations A * X = B with a symmetric positive definite tridiagonal matrix A using the factorization A = L*D*L**T or A = U**T*D*U computed by DPTTRF. (The two forms are equivalent if A is real.) ARGUMENTS N (input) INTEGER The order of the tridiagonal matrix A. N >= 0. NRHS (input) INTEGER The number of right hand sides, i.e., the number of columns of the matrix B. NRHS >= 0. D (input) DOUBLE PRECISION array, dimension (N) The n diagonal elements of the diagonal matrix D from the factorization computed by DPTTRF. E (input) DOUBLE PRECISION array, dimension (N-1) The (n-1) off-diagonal elements of the unit bidiago- nal factor U or L from the factorization computed by DPTTRF. (LDB,NRHS) B (input/output) DOUBLE PRECISION array, dimension On entry, the right hand side matrix B. On exit, the solution matrix X. LDB (input) INTEGER The leading dimension of the array B. LDB >= max(1,N). INFO (output) INTEGER = 0: successful exit < 0: if INFO = -i, the i-th argument had an illegal value