Sollya User's Manual

Name:

isevaluable tests whether a function can be evaluated at a point

Usage:

isevaluable(function, constant) : (function, constant) -> boolean

Parameters:

function represents a function
constant represents a constant point

Description:

isevaluable applied to function function and a constant constant returns a boolean indicating whether or not a subsequent call to evaluate on the same function function and constant constant will produce a numerical result or NaN. This means isevaluable returns false iff evaluate will return NaN.

Example 1:

   > isevaluable(sin(pi * 1/x), 0.75);
   true
   > print(evaluate(sin(pi * 1/x), 0.75));
   -0.86602540378443864676372317075293618347140262690518

Example 2:

   > isevaluable(sin(pi * 1/x), 0.5);
   true
   > print(evaluate(sin(pi * 1/x), 0.5));
   [-1.72986452514381269516508615031098129542836767991679e-12715;7.5941198201187963145069564314525661706039084390067e-12716]

Example 3:

   > isevaluable(sin(pi * 1/x), 0);
   false
   > print(evaluate(sin(pi * 1/x), 0));
   [@NaN@;@NaN@]