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psb_geamax -- Infinity-Norm of Vector

This function computes the infinity-norm of a vector $x$.
If $x$ is a real vector it computes infinity norm as:

\begin{displaymath}amax \leftarrow \max_i \vert x_i\vert\end{displaymath}

else if $x$ is a complex vector then it computes infinity-norm as:

\begin{displaymath}amax \leftarrow \max_i {(\vert re(x_i)\vert + \vert im(x_i)\vert)}\end{displaymath}

psb_geamax(x, desc_a, info)


Table 4: Data types
$amax$ $x$ Function
Short Precision Real Short Precision Real psb_geamax
Long Precision Real Long Precision Real psb_geamax
Short Precision Real Short Precision Complex psb_geamax
Long Precision Real Long Precision Complex psb_geamax


Type:
Synchronous.
On Entry
x
the local portion of global dense matrix $x$.
Scope: local
Type: required
Intent: in.
Specified as: a rank one or two array containing numbers of type specified in Table 4.
desc_a
contains data structures for communications.
Scope: local
Type: required
Intent: in.
Specified as: a structured data of type descdatapsb_desc_type.

On Return
Function value
is the infinity norm of subvector $x$.
Scope: global
Specified as: a long precision real number.
info
Error code.
Scope: local
Type: required
Intent: out.
An integer value; 0 means no error has been detected.


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Next: psb_geamaxs Generalized Up: Computational routines Previous: psb_gedots Generalized   Contents