LAPACK
3.4.2
LAPACK: Linear Algebra PACKage

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Functions/Subroutines  
subroutine  slacon (N, V, X, ISGN, EST, KASE) 
SLACON estimates the 1norm of a square matrix, using reverse communication for evaluating matrixvector products. 
subroutine slacon  (  integer  N, 
real, dimension( * )  V,  
real, dimension( * )  X,  
integer, dimension( * )  ISGN,  
real  EST,  
integer  KASE  
) 
SLACON estimates the 1norm of a square matrix, using reverse communication for evaluating matrixvector products.
Download SLACON + dependencies [TGZ] [ZIP] [TXT]SLACON estimates the 1norm of a square, real matrix A. Reverse communication is used for evaluating matrixvector products.
[in]  N  N is INTEGER The order of the matrix. N >= 1. 
[out]  V  V is REAL array, dimension (N) On the final return, V = A*W, where EST = norm(V)/norm(W) (W is not returned). 
[in,out]  X  X is REAL array, dimension (N) On an intermediate return, X should be overwritten by A * X, if KASE=1, A**T * X, if KASE=2, and SLACON must be recalled with all the other parameters unchanged. 
[out]  ISGN  ISGN is INTEGER array, dimension (N) 
[in,out]  EST  EST is REAL On entry with KASE = 1 or 2 and JUMP = 3, EST should be unchanged from the previous call to SLACON. On exit, EST is an estimate (a lower bound) for norm(A). 
[in,out]  KASE  KASE is INTEGER On the initial call to SLACON, KASE should be 0. On an intermediate return, KASE will be 1 or 2, indicating whether X should be overwritten by A * X or A**T * X. On the final return from SLACON, KASE will again be 0. 
Definition at line 116 of file slacon.f.