Visible to Intel only — GUID: GUID-442ED2EE-056D-4235-AA43-9860CD7586D3
Visible to Intel only — GUID: GUID-442ED2EE-056D-4235-AA43-9860CD7586D3
p?lacon
Estimates the 1-norm of a square matrix, using the reverse communication for evaluating matrix-vector products.
Syntax
call pslacon(n, v, iv, jv, descv, x, ix, jx, descx, isgn, est, kase)
call pdlacon(n, v, iv, jv, descv, x, ix, jx, descx, isgn, est, kase)
call pclacon(n, v, iv, jv, descv, x, ix, jx, descx, isgn, est, kase)
call pzlacon(n, v, iv, jv, descv, x, ix, jx, descx, isgn, est, kase)
Description
The p?laconroutine estimates the 1-norm of a square, real/unitary distributed matrix A. Reverse communication is used for evaluating matrix-vector products. x and v are aligned with the distributed matrix A, this information is implicitly contained within iv, ix, descv, and descx.
Input Parameters
- n
-
(global) INTEGER. The length of the distributed vectors v and x. n ≥ 0.
- v
-
(local).
REAL for pslacon
DOUBLE PRECISION for pdlacon
COMPLEX for pclacon
COMPLEX*16 for pzlacon.
Pointer into the local memory to an array of size LOCr(n+mod(iv-1, mb_v)). On the final return, v = a*w, where est = norm(v)/norm(w) (w is not returned).
- iv, jv
-
(global) INTEGER. The row and column indices in the global matrix V indicating the first row and the first column of the submatrix V, respectively.
- descv
-
(global and local) INTEGER array of size dlen_. The array descriptor for the distributed matrix V.
- x
-
(local).
REAL for pslacon
DOUBLE PRECISION for pdlacon
COMPLEX for pclacon
COMPLEX*16 for pzlacon.
Pointer into the local memory to an array of size LOCr(n+mod(ix-1, mb_x)).
- ix, jx
-
(global) INTEGER. The row and column indices in the global matrix X indicating the first row and the first column of the submatrix X, respectively.
- descx
-
(global and local) INTEGER array of size dlen_. The array descriptor for the distributed matrix X.
- isgn
-
(local). INTEGER.
Array of size LOCr(n+mod(ix-1, mb_x)). isgn is aligned with x and v.
- kase
-
(local). INTEGER.
On the initial call to p?lacon, kase should be 0.
Output Parameters
- x
-
(local).
On an intermediate return, X should be overwritten by A*X, if kase=1, A' *X, if kase=2,
p?lacon must be re-called with all the other parameters unchanged.
- est
-
(global). REAL for single precision flavors
DOUBLE PRECISION for double precision flavors
- kase
-
(local)
INTEGER. On an intermediate return, kase is 1 or 2, indicating whether X should be overwritten by A*X, or A'*X. On the final return from p?lacon, kase is again 0.