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44 lines
1.2 KiB
C++
44 lines
1.2 KiB
C++
Fig10_38.cpp - Simple matrix multiplication algorithm with a test program
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#include <iostream.h>
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#include "matrix.h"
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/* START: Fig10_38.txt */
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/**
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* Standard matrix multiplication.
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* Arrays start at 0.
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* Assumes a and b are square.
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*/
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matrix<int> operator*( const matrix<int> & a, const matrix<int> & b )
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{
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int n = a.numrows( );
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matrix<int> c( n, n );
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int i;
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for( i = 0; i < n; i++ ) // Initialization
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for( int j = 0; j < n; j++ )
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c[ i ][ j ] = 0;
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for( i = 0; i < n; i++ )
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for( int j = 0; j < n; j++ )
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for( int k = 0; k < n; k++ )
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c[ i ][ j ] += a[ i ][ k ] * b[ k ][ j ];
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return c;
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}
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/* END */
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int main( )
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{
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matrix<int> a( 2, 2 );
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a[ 0 ][ 0 ] = 1; a[ 0 ][ 1 ] = 2;
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a[ 1 ][ 0 ] = 3; a[ 1 ][ 1 ] = 4;
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matrix<int> c = a * a;
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cout << c[ 0 ][ 0 ] << " " << c[ 0 ][ 1 ] << endl <<
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c[ 1 ][ 0 ] << " " << c[ 1 ][ 1 ] << endl;
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return 0;
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}
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