is_lower, is_upper, is_triangle, is_unit -- Format check

if (a%is_triangle()) then 
if (a%is_upper()) then 
if (a%is_lower()) then 
if (a%is_unit()) then 

Type:

Asynchronous.

On Entry

a

the sparse matrix
Scope: local

On Return

Function value

A logical value indicating whether the matrix is triangular; if is_triangle() returns .true. check also if it is lower, upper and with a unit (i.e. assumed) diagonal.