Re: Another question about Compile[]:
- To: mathgroup at smc.vnet.net
- Subject: [mg50056] Re: Another question about Compile[]:
- From: "Mariusz Jankowski" <mjankowski at usm.maine.edu>
- Date: Fri, 13 Aug 2004 05:56:05 -0400 (EDT)
- Organization: University of Southern Maine
- References: <cf22mp$7si$1@smc.vnet.net>
- Sender: owner-wri-mathgroup at wolfram.com
Gilmar, the first argument of Compile is the input list, so variables p and
q should be removed. Try
mgppp = Compile[{ {n, _Integer, 1}}, etc...]
However, I suspect your compiled code will be slower. Most of the work is
done inside kernel functions, which I suspect cannot be made faster by
wrapping with compile.
Regards, Mariusz
>>> Gilmar Rodr?guez Pierluissi<gilmar.rodriguez at nwfwmd.state.fl.us>
8/7/2004 4:08:57 AM >>>
Dear Mathematica Web Group:
I'm attempting to build a Compiled version of the following function:
In[1]:
MGPPP[n_] := Module[{p, q},
{m = n/2; If[Element[m,
Primes], {p = m, q = m}, {k =
PrimePi[m]; Do[If[Element[n - Prime[i], Primes], hit = i;
Break[]], {i, k, 1, -1}], p = Prime[hit], q = n - p}]}; {p, q}]
which works as follows:
In[2]:
MGPPP[400]
Out[2]:
{173, 227}
Unfortunately, my attempt fails:
In[3]:
mgppp = Compile[{{p, _Integer,
1}, {q, _Integer, 1}, {n, _Integer, 1}}, Module[{p, q},
{m = n/2; If[Element[m, Primes], {p = m, q = m}, {
k = PrimePi[m]; Do[If[Element[n - Prime[i],
Primes], hit = i;
Break[]], {i, k, 1, -1}], p = Prime[hit], q = n - p}]}; {p, q}]]
Out[3]:
Compile::initvar: The variable p has not been initialized or has been \
initialized to Null.
Compile::cptype: List not supported for type Void; evaluation will use the
\
uncompiled function.
Thank you for your help!