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Non-numeric arguments to Compile-d functions
*To*: mathgroup at smc.vnet.net
*Subject*: [mg82117] Non-numeric arguments to Compile-d functions
*From*: "Andrew Moylan" <andrew.j.moylan at gmail.com>
*Date*: Fri, 12 Oct 2007 03:02:15 -0400 (EDT)
Here's a compiled function that does some (made-up) operation on a
real-valued function f:
Compile[{},
Do[If[f[i] < 0, Return[{i, f[i]}]], {i, 10}],
{{f[_], _Real}}
]
(It finds the first integer i such that f[i] is negative.)
For the usual reasons of modularity, I would like to make compiled functions
like this not refer to global variables named f. (We can't put f as one of
the elements of the first argument to compile, because those must all be
numeric scalars or arrays.)
Here's one way to do this:
Module[
{f, compiledpart},
compiledpart = Compile[{},
Do[If[f[i] < 0, Return[{i, f[i]}]], {i, 10}],
{{f[_], _Real}}
];
findfirstnegative[tempf_] := (compiledpart /. f -> tempf)[]
]
I don't really like this solution because we needed to use two names (f and
tempf). Using two names per argument could get messy if there are several
non-numeric arguments instead of just f.
Is this the recommended method for compiling "as much of a function as
possible"?
Note that the following attempt (which doesn't need a tempf) doesn't work:
With[{rhs = compiledpart}, findfirstnegative[f_] := rhs]
It fails because Mathematica automatically renames the f in the
CompiledFunction in compiledpart to *avoid* the very naming clash I am
trying to create. The With statement effectively creates:
findfirstnegative[f$_] := CompiledFunction[{},
Do[If[f$851[i]<0, Return[{i,f$851[i]}]], {i,10}],
-CompiledCode-
]
What's the neatest, "right" way to make compiled functions that take
non-numeric arguments?
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