-- Using EVVEXPR to Process Vector Expressions
A new expression evaluator evvexpr() is available in the IRAF
programming environment starting with V2.10.3BETA. This is similar to the
old expression evaluator evexpr() except that it will operate on and
can return vector operands, supports mixed scalar-vector expressions and a
wider range of data types, and provides a number of new intrinstic
functions. The conventional arithmetic, trigonometric, and type conversion
intrinsic functions are available plus a number of projection functions
(e.g., length of a vector, median value of a vector, etc.) and miscellaneous
other functions. In addition there is a mechanism by which applications
programs can define and use their own custom intrinsic functions.
This function is used in the new imexpr
and import/export tasks
(see accompanying articles) to evaluate expressions using image operands.
It can also be used to evaluate scalar expressions and it is recommended
that evvexpr be used for new tasks instead of the older evexpr,
which is considered obsolete. For more information see the
imexpr
help page, the sys$fmtio/evvexpr.gy source file, or contact the IRAF
group (iraf.noao.edu).
Doug Tody, Mike Fitzpatrick
This document was translated by ms2html v1.8 on 21Jan95.