Function won't compile. Is there a workaround?

Question

Here's a simplified form of a function I would like to compile, but it produces errors

DataType = Compile[{{Inputdata, _Real, 1}}, Module[{CIEL, CIEa, CIEb},
    dim = Dimensions@Inputdata;
    If[dim[[1]] > 3,
     {CIEL, CIEa, CIEb} = Inputdata
        ]
    ],
   CompilationTarget -> "C"
   ];

The error Mathematica produces is:

Compile::extscalar: dim=Dimensions[Inputdata] cannot be compiled and will be evaluated externally. The result is assumed to be of type Void. >>

Is there a workaround to allow these types of functions to compile for conditionals that depend on the dimensions of a list?

You are setting global variables from inside the compiled function, I don't think that is possible, is that your intention? What should the function return? — s0rce, Nov 27 '13 at 02:55
If (Dimensions@Inputdata)[[1]] > 3 then you can't set {CIEL, CIEa, CIEb} = Inputdata since Dimensions@{CIEL, CIEa, CIEb} == {3}. — s0rce, Nov 27 '13 at 03:21
@s0rce The error is above this part of the function. so change that to whatever and the error is the same — Nothingtoseehere, Nov 27 '13 at 03:37
It compiles for me, try a fresh kernel. What version are you using, I'm using 9. — s0rce, Nov 27 '13 at 03:42

score 0 · Answer 1 · answered Nov 27 '13 at 02:58

0

Conditionals are fine in compiled functions...

DataType = Compile[{{Inputdata, _Real, 1}},
   If[Length@Inputdata > 3, 1, 0], CompilationTarget -> "C"];

DataType[{5, 6, 7}]

(* 0 *)

DataType[{5, 6, 7, 8}]

(* 1 *)

The problem is your function returns nothing, you are trying to set global variables from inside the compiled function and also you never use a, b, and c.

answered Nov 27 '13 at 02:58

s0rce

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Length won't work in this case. I changed the variable names at the last minute and just chose the wrong names. fixed – Nothingtoseehere Nov 27 '13 at 03:08
Isn't Length equivalent to the first element in the output of Dimensions? – s0rce Nov 27 '13 at 03:19
It is but because dim is used multiple times I need Dimensions. – Nothingtoseehere Nov 27 '13 at 03:36

Function won't compile. Is there a workaround?

1 Answers1