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Blitz Support : |
From: Breeveld, Eddie \(Reigate\) (Eddie.Breeveld_at_[hidden])
Date: 2005-04-04 07:01:29
Hi Derrick and Patrick,
This is brilliant! My C++ is 'improving', and the routine Derrick
suggested works. I have modified Derrick's suggestion by using a cast
to remove the temporary array, and I'm also passing the array as a const
by reference to avoid too much copying:
template<class T_expr> inline
typename _bz_ArrayExpr<T_expr>::T_numtype
Afun(const blitz::_bz_ArrayExpr<T_expr> &expr)
{
typedef blitz::_bz_ArrayExpr<T_expr> exprT;
return Afun(
(blitz::Array<typename exprT::T_numtype, exprT::rank>)expr );
}
I am now trying to do something similar for functions that return arrays
different shapes to the original. What are the other class members of
_bz_ArrayExpr?
Patrick, a sample program that does not compile in Microsoft VS.NET 7.1
would be
#include "c:\program files\blitz-0.8\blitz\array.h"
BZ_USING_NAMESPACE(blitz)
template<typename T, int N> inline
T RTSumAll(const Array<T,N> A)
{
// complex processing in here ...
return sum(A);
};
int main(int argc, char* argv[])
{
Array<double, 2> fund(2,2);
fund = 3.0;
double rate = RTSumAll(fund * 6.0);
}
It would be interesting to know if it works with other compilers.
All the best,
Eddie
-----Original Message-----
From: Derrick Bass
Sent: 04 April 2005 09:44
To: Breeveld, Eddie (Reigate)
Subject: Re: [Blitz-support] Functions that take array expressions
There is no way to do this directly. If you are really good at C++, you
can take a look at the code for similar blitz functions like sum() and
try to do something similar. If you are willing to have a single
temporary array, though, then something like this should work:
template<class T_expr>
inline
typename _bz_ArrayExpr<T_expr>::T_numtype Afun( blitz::_bz_ArrayExpr<
T_expr> expr) {
typedef blitz::_bz_ArrayExpr<T_expr> exprT;
blitz::Array< typename exprT::T_numtype, exprT::rank > A( expr
);
return Afun( A );
}
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