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/*
* Copyright (c) 2009 Samit Basu
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation; either version 2 of the License, or
* (at your option) any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program; if not, write to the Free Software
* Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
*
*/
#include "Operators.hpp"
#include "Math.hpp"
#include "Complex.hpp"
struct OpVecProd {
template <typename T>
static inline void func(ConstSparseIterator<T> & src,
SparseSlice<T>& dest) {
T result = 1;
index_t count = 0;
index_t col = src.col();
while (src.col() == col) {
count++;
result = result * src.value();
src.next();
}
if (count < src.rows())
result = 0;
dest[1] = result;
}
template <typename T>
static inline void func(ConstComplexSparseIterator<T> & src,
SparseSlice<T>& dest_real,
SparseSlice<T>& dest_imag) {
T result_real = 1;
T result_imag = 0;
index_t count = 0;
index_t col = src.col();
while (src.col() == col) {
count++;
complex_multiply(result_real,result_imag,src.realValue(),src.imagValue(),
result_real,result_imag);
src.next();
}
if (count < src.rows()) {
result_real = 0;
result_imag = 0;
}
dest_real[1] = result_real;
dest_imag[1] = result_imag;
}
template <typename T>
static inline void func(const BasicArray<T> & src,
BasicArray<T>& dest) {
T result = 1;
for (index_t i=1;i<=src.length();i++)
result = result * src[i];
dest[1] = result;
}
template <typename T>
static inline void func(const BasicArray<T> & src_real,
const BasicArray<T> & src_imag,
BasicArray<T>& dest_real,
BasicArray<T>& dest_imag) {
T result_real = 1;
T result_imag = 0;
for (index_t i=1;i<=src_real.length();i++) {
T temp_real, temp_imag;
complex_multiply(result_real,result_imag,
src_real[i],src_imag[i],
temp_real,temp_imag);
result_real = temp_real;
result_imag = temp_imag;
}
dest_real[1] = result_real;
dest_imag[1] = result_imag;
}
};
//!
//@Module PROD Product Function
//@@Section ELEMENTARY
//@@Usage
//Computes the product of an array along a given dimension. The general
//syntax for its use is
//@[
// y = prod(x,d)
//@]
//where @|x| is an @|n|-dimensions array of numerical type.
//The output is of the same numerical type as the input, except
//for integer types, which are automatically promoted to @|int32|.
// The argument @|d| is optional, and denotes the dimension along
//which to take the product. The output is computed via
//\[
// y(m_1,\ldots,m_{d-1},1,m_{d+1},\ldots,m_{p}) =
// \prod_{k} x(m_1,\ldots,m_{d-1},k,m_{d+1},\ldots,m_{p})
//\]
//If @|d| is omitted, then the product is taken along the
//first non-singleton dimension of @|x|. Note that by definition
//(starting with FreeMat 2.1) @|prod([]) = 1|.
//@@Example
//The following piece of code demonstrates various uses of the product
//function
//@<
//A = [5,1,3;3,2,1;0,3,1]
//@>
//We start by calling @|prod| without a dimension argument, in which case it defaults to the first nonsingular dimension (in this case, along the columns or @|d = 1|).
//@<
//prod(A)
//@>
//Next, we take the product along the rows.
//@<
//prod(A,2)
//@>
//@@Tests
//@$exact#y1=prod(x1)
//@@Signature
//function prod ProdFunction
//inputs x dimension
//outputs y
//!
ArrayVector ProdFunction(int nargout, const ArrayVector& arg) {
// Get the data argument
if (arg.size() < 1)
throw Exception("prod requires at least one argument");
Array input(arg[0]);
int dim;
if (arg.size() > 1)
dim = arg[1].asInteger()-1;
else
dim = input.dimensions().firstNonsingular();
if (input.isEmpty() && input.is2D()) return ArrayVector(Array(1.0));
return ArrayVector(VectorOp<OpVecProd>(input,1,dim));
}
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