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Re: x=2;Composition[f,FindMinimum][x+1,{x,a}]


I was testing to see if I could get around the HoldAll Attribute of
FindMinimum by using Composition.

Due to the Attributes of Composition, one would think that
Composition[FindMinimum][args] would cause args to be evaluated before
being caught by FindMinimum's HoldAll. But no. For some reason, it
behaves like FindMinimum[args] - some sort of short circuit for
performance reasons? Perhaps this optimization should be documented
(or maybe it already is and I am too blind to find it).

However, based on a Trace someone kindly sent to me,
Composition[f,FindMinimum][args] in the older versions do cause the
arguments to be evaluated before FindMinimum's HoldAll takes effect.

It's just that in the latest version, if f does not also have the
attribute HoldAll, then the kernel crashes...

Darned if one does, and darned if one doesn't - at least in 5.2 :-)

-- 
http://chris.chiasson.name/


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