Re: Testing for unevaluated functions

*To*: mathgroup at yoda.physics.unc.edu*Subject*: Re: Testing for unevaluated functions*From*: David Withoff <withoff>*Date*: Tue, 29 Sep 1992 09:02:05 -0500

> I would like to build a function that uses FindMinimum to search for a > minimum (obviously). The problem is that as one varies one of the parameters > of the function, a definite min. will move outside of the range of the search. > > I would like to test for this condition, and if Find Minimum cannot find a > minimum=, then use one of the endpoints. > > The question is, is there no general mechanism for testing the return status > of a function, or at least a built-in function? > > Thanks in advance for any info/suggestions. > > jake This isn't a direct answer to your question, but it might be useful anyway: In[17]:= f[s_] := Check[FindMinimum[(x-s)^2, {x, 0, -1, 1}], {(Abs[s] - 1)^2, {x -> Sign[s]}}, FindMinimum::regex] In[18]:= f[.5] Out[18]= {0., {x -> 0.5}} In[19]:= f[2] FindMinimum::regex: Reached the point {0.} + 1. {1.} which is outside the region {{-1., 1.}}. Out[19]= {1, {x -> 1}} In[20]:= f[-3] FindMinimum::regex: Reached the point 1. {-1.} + {0.} which is outside the region {{-1., 1.}}. Out[20]= {4, {x -> -1}}