UNPACK(3I) Last changed: 1-6-98
NAME
UNPACK - Unpacks an array of rank one into an array under control of a
mask
SYNOPSIS
UNPACK ([VECTOR=]vector, [MASK=]mask, [FIELD=]field)
IMPLEMENTATION
UNICOS, UNICOS/mk, and IRIX systems
STANDARDS
Fortran 90
DESCRIPTION
The UNPACK intrinsic function unpacks an array of rank one into an
array under control of mask. It accepts the following arguments:
vector Can be of any type. It must have rank one. Its size must
be at least t where t is the number of true elements in
mask.
mask Must be of type logical and array valued.
field Must be of the same type as vector, and must be conformable
with mask.
UNPACK is a transformational function. The name of this intrinsic
cannot be passed as an argument.
RETURN VALUES
The result is an array of the same type as vector and the same shape
as mask.
The element of the result that corresponds to the ith true element of
mask, in array element order, has the value vector(i) for i=1, 2, ...,
t where t is the number of true values in mask. Each other element
has the value equal to field if field is scalar or to the
corresponding element of field if it is an array.
EXAMPLES
This example uses UNPACK to scatter specific values to specific
positions in an array.
Assume that M is the following array:
| 1 0 0 |
| 0 1 0 |
| 0 0 1 |
Assume that V is the array [1, 2, 3].
Assume that Q is the logical mask:
| F T F |
| T F F |
| F F T |
In logical mask Q, T represents true and F represents false, so
UNPACK(V, MASK=Q, FIELD=M) has the following value:
| 1 2 0 |
| 1 1 0 |
| 0 0 3 |
The result of UNPACK(V, MASK=Q, FIELD=0) has the following value:
| 0 2 0 |
| 1 0 0 |
| 0 0 3 |
SEE ALSO
Intrinsic Procedures Reference Manual, publication SR-2138, for the
printed version of this man page.
