program to add sparse matrix
#include <stdio.h>#include <conio.h>
#include <alloc.h>
#define MAX1 3
#define MAX2 3
#define MAXSIZE 9
#define BIGNUM 100
struct sparse
{
int *sp ;
int row ;
int *result ;
} ;
void initsparse ( struct sparse * ) ;
void create_array ( struct sparse * ) ;
int count ( struct sparse ) ;
void display ( struct sparse ) ;
void create_tuple ( struct sparse *, struct sparse ) ;
void display_tuple ( struct sparse ) ;
void addmat ( struct sparse *, struct sparse, struct sparse ) ;
void display_result ( struct sparse ) ;
void delsparse ( struct sparse * ) ;
void main( )
{
struct sparse s[5] ;
int i ;
clrscr( ) ;
for ( i = 0 ; i <= 4 ; i++ )
initsparse ( &s[i] ) ;
create_array ( &s[0] ) ;
create_tuple ( &s[1], s[0] ) ;
display_tuple ( s[1] ) ;
create_array ( &s[2] ) ;
create_tuple ( &s[3], s[2] ) ;
display_tuple ( s[3] ) ;
addmat ( &s[4], s[1], s[3] ) ;
printf ( "\nResult of addition of two matrices: " ) ;
display_result ( s[4] ) ;
for ( i = 0 ; i <= 4 ; i++ )
delsparse ( &s[i] ) ;
getch( ) ;
}
/* initialises structure elements */
void initsparse ( struct sparse *p )
{
p -> sp = NULL ;
p -> result = NULL ;
}
/* dynamically creates the matrix */
void create_array ( struct sparse *p )
{
int n, i ;
/* allocate memory */
p -> sp = ( int * ) malloc ( MAX1 * MAX2 * sizeof ( int ) ) ;
/* add elements to the array */
for ( i = 0 ; i < MAX1 * MAX2 ; i++ )
{
printf ( "Enter element no. %d:", i ) ;
scanf ( "%d", &n ) ;
* ( p -> sp + i ) = n ;
}
}
/* displays the contents of the matrix */
void display ( struct sparse s )
{
int i ;
/* traverses the entire matrix */
for ( i = 0 ; i < MAX1 * MAX2 ; i++ )
{
/* positions the cursor to the new line for every new row */
if ( i % MAX2 == 0 )
printf ( "\n" ) ;
printf ( "%d\t", * ( s.sp + i ) ) ;
}
}
/* counts the number of non-zero elements */
int count ( struct sparse s )
{
int cnt = 0, i ;
for ( i = 0 ; i < MAX1 * MAX2 ; i++ )
{
if ( * ( s.sp + i ) != 0 )
cnt++ ;
}
return cnt ;
}
/* creates an array that stores information about non-zero elements */
void create_tuple ( struct sparse *p, struct sparse s )
{
int r = 0 , c = -1, l = -1, i ;
/* get the total number of non-zero elements
and add 1 to store total no. of rows, cols, and non-zero values */
p -> row = count ( s ) + 1 ;
/* allocate memory */
p -> sp = ( int * ) malloc ( p -> row * 3 * sizeof ( int ) ) ;
/* store information about
total no. of rows, cols, and non-zero values */
* ( p -> sp + 0 ) = MAX1 ;
* ( p -> sp + 1 ) = MAX2 ;
* ( p -> sp + 2 ) = p -> row - 1 ;
l = 2 ;
/* scan the array and store info. about non-zero values in the 3-tuple */
for ( i = 0 ; i < MAX1 * MAX2 ; i++ )
{
c++ ;
/* sets the row and column values */
if ( ( ( i % MAX2 ) == 0 ) && ( i != 0 ) )
{
r++ ;
c = 0 ;
}
/* checks for non-zero element row, column and non-zero element value is assigned to the matrix */
if ( * ( s.sp + i ) != 0 )
{
l++ ;
* ( p -> sp + l ) = r ;
l++ ;
* ( p -> sp + l ) = c ;
l++ ;
* ( p -> sp + l ) = * ( s.sp + i ) ;
}
}
}
/* displays the contents of the matrix */
void display_tuple ( struct sparse s )
{
int i, j ;
/* traverses the entire matrix */
printf ( "\nElements in a 3-tuple: \n" ) ;
j = ( * ( s.sp + 2 ) * 3 ) + 3 ;
for ( i = 0 ; i < j ; i++ )
{
/* positions the cursor to the new line for every new row */
if ( i % 3 == 0 )
printf ( "\n" ) ;
printf ( "%d\t", * ( s.sp + i ) ) ;
}
printf ( "\n" ) ;
}
/* carries out addition of two matrices */
void addmat ( struct sparse *p, struct sparse s1, struct sparse s2 )
{
int i = 1, j = 1, k = 1 ;
int elem = 1 ;
int max, amax, bmax ;
int rowa, rowb, cola, colb, vala, valb ;
/* get the total number of non-zero values from both the matrices */
amax = * ( s1.sp + 2 ) ;
bmax = * ( s2.sp + 2 ) ;
max = amax + bmax ;
/* allocate memory for result */
p -> result = ( int * ) malloc ( MAXSIZE * 3 * sizeof ( int ) ) ;
while ( elem <= max )
{
/* check if i < max. non-zero values
in first 3-tuple and get the values */
if ( i <= amax )
{
rowa = * ( s1.sp + i * 3 + 0 ) ;
cola = * ( s1.sp + i * 3 + 1 ) ;
vala = * ( s1.sp + i * 3 + 2 ) ;
}
else
rowa = cola = BIGNUM ;
/* check if j < max. non-zero values in secon 3-tuple and get the values */
if ( j <= bmax )
{
rowb = * ( s2.sp + j * 3 + 0 ) ;
colb = * ( s2.sp + j * 3 + 1 ) ;
valb = * ( s2.sp + j * 3 + 2 ) ;
}
else
rowb = colb = BIGNUM ;
/* if row no. of both 3-tuple are same */
if ( rowa == rowb )
{
/* if col no. of both 3-tuple are same */
if ( cola == colb )
{
/* add tow non-zero values
store in result */
* ( p -> result + k * 3 + 0 ) = rowa ;
* ( p -> result + k * 3 + 1 ) = cola ;
* ( p -> result + k * 3 + 2 ) = vala + valb ;
i++ ;
j++ ;
max-- ;
}
/* if col no. of first 3-tuple is < col no. of second 3-tuple, then add info. as it is to result */
if ( cola < colb )
{
* ( p -> result + k * 3 + 0 ) = rowa ;
* ( p -> result + k * 3 + 1 ) = cola ;
* ( p -> result + k * 3 + 2 ) = vala ;
i++ ;
}
/* if col no. of first 3-tuple is > col no. of second 3-tuple, then add info. as it is to result */
if ( cola > colb )
{
* ( p -> result + k * 3 + 0 ) = rowb ;
* ( p -> result + k * 3 + 1 ) = colb ;
* ( p -> result + k * 3 + 2 ) = valb ;
j++ ;
}
k++ ;
}
/* if row no. of first 3-tuple is < row no. of second 3-tuple, then add info. as it is to result */
if ( rowa < rowb )
{
* ( p -> result + k * 3 + 0 ) = rowa ;
* ( p -> result + k * 3 + 1 ) = cola ;
* ( p -> result + k * 3 + 2 ) = vala ;
i++ ;
k++ ;
}
/* if row no. of first 3-tuple is > row no. of second 3-tuple, then add info. as it is to result */
if ( rowa > rowb )
{
* ( p -> result + k * 3 + 0 ) = rowb ;
* ( p -> result + k * 3 + 1 ) = colb ;
* ( p -> result + k * 3 + 2 ) = valb ;
j++ ;
k++ ;
}
elem++ ;
}
/* add info about the total no. of rows, cols, and non-zero values that the resultant array contains to the result */
* ( p -> result + 0 ) = MAX1 ;
* ( p -> result + 1 ) = MAX2 ;
* ( p -> result + 2 ) = max ;
}
/* displays the contents of the matrix */
void display_result ( struct sparse s )
{
int i ;
/* traverses the entire matrix */
for ( i = 0 ; i < ( * ( s.result + 0 + 2 ) + 1 ) * 3 ; i++ )
{
/* positions the cursor to the new line for every new row */
if ( i % 3 == 0 )
printf ( "\n" ) ;
printf ( "%d\t", * ( s.result + i ) ) ;
}
}
/* deallocates memory */
void delsparse ( struct sparse *p )
{
if ( p -> sp != NULL )
free ( p -> sp ) ;
if ( p -> result != NULL )
free ( p -> result ) ;
}
Sparse matrices, which are common in scientific applications, are matrices in which most elements are zero. To save space and running time it is critical to only store the nonzero elements. A standard representation of sparse matrices in sequential languages is to use an array with one element per row each of which contains a linked-list of the nonzero values in that row along with their column number. A similar representation can be used in parallel. In NESL a sparse matrix can be represented as a sequence of rows, each of which is a sequence of (column-number, value) pairs of the nonzero values in the row
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