multiplying a 2D array by a 1D array

my second function does not seem to work. It is supposed to multiply each row of a 2D array by a 1D array. Im reading in a 2D and a 1D array from a file using I/O redirection <data1.txt > out1.txt. Can somebody point out the problem im doing. It does not print numbers.

Code:

#include<stdio.h>

#define SIZE 100

void calcSumAs(double a[][SIZE], double y[], int m, int n);
void calcSumAXs(double a[][SIZE], double y[], double rs[], int m, int n);

int main(void)
{
	int m;
	int n;
	int i;
	int j;
	double ar[SIZE];
	double prod[SIZE];
	double mx[SIZE][SIZE];
	double sum[SIZE];
	double Y;
	scanf("%d%d", &m, &n);
	
	for (i = 0; i < m; i++)
	{
		for (j = 0; j < n; j++)
			scanf("%lf", &mx[i][j]);
	}
	
	for (i = 0; i < m; i++)
		scanf("%lf", &ar[i]);
	
	calcSumAs(mx, sum, m, n);
	calcSumAXs(mx, ar, prod, m, n);
	
	for (i = 0; i < m; i++)
		printf("%lf ", prod[i]);	
	

	
	return 0;
}

void calcSumAs(double a[][SIZE], double y[], int m, int n)
{
	int i, j;
	for (i = 0; i < m; i++)
		for (y[i] = 0, j = 0; j < n; j++)
			y[i] += a[i][j];
	return;
}

void calcSumAXs(double a[][SIZE], double y[], double rs[], int m, int n)
{
	int i, j;
	
	for(i = 0; i < m; i++)
		for(rs[i] = 0, j = 0; j < n; j++)
			rs[i] += a[i][j] * y[j];
	return;
}

Code:

for each row
    for each column
        dosomethingwith: onedeearray[ col ] * twodeearray[ row ][ col ]

There's the general idea.

Are you sure what you're really doing is what you mean to be doing?


Quzah.

yes, i know everything is correct but im not getting the numbers printed, the problem is in my second function and i tried it, can you give me some more advice please.

When you say you're not getting the numbers printed, what exactly does that mean? You input numbers and ... ? Your program ends early? It prints stuff, but it's not what you expect? What exactly?


Quzah.

the last loop in the main function is supposed to print the sums of the products of a one D array and the 2 D array. It prints the works of the second function. What is printed is this 1.#QNAN0 1.#QNAN0 1.#QNAN0 -1.#QNAN0 1.#QNAN0 1.#QNAN0 , instead its supposed to be five numbers.

sorry i mean 6 numbers

i know the loop executes six times which is correct its just not printing out the sums of the products of the 1 d array and 2d array

The #QNAN is a "not-a-number indication". The most obvious cause for this is that the number is "an illegal bitcombination", and that's usually caused by not initializing the floating point value correctly (such as not initializing it at all).

Check your variables that you calculate with and make sure everything is set an appropriate initial value.

--
Mats

i checked my code over and over again and i cant seem to find a problem. Please take a look at my program and see if i made a mistake anywhere.

I can't get any NaN output. What input are you using?

6 11
21 22 23 24 25 26 27 28 29 30 31
-21 -22 -23 -24 -25 -26 -27 -28 -29 -30 -31
0 1 0 1 0 1 0 1 0 1 0
1 2 3 4 5 6 7 8 9 10 11
12 13 14 15 16 17 18 19 20 21 22
11 10 9 8 7 6 5 4 3 2 1
0 1 -1 0 1 -1 0 1 -1 0 1

this is the imput from a file, the first function is supposed to calculate the sum of each row which works fine. The second function is supposed to multiply each row by the last row of the input

And the program returns -2, 2, 0, -2, -2, 2. Is that not what you want?

the number for the first row is supposed to be 28, i havent calculated the other ones

it doesnt return any numbers it all it returns 1.#QNAN0 1.#QNAN0 1.#QNAN0 1.#QNAN0 1.#QNAN0 1.#QNAN0. Instead its supposed to return 6 floating point numbers, the first one being 28

Stop reading it from a file for starters, and instead stick it in a fixed array and see if it gives you what you expect:

Code:

#include<stdio.h>

void foo( int bar[], int baz[][ 5 ], size_t r, size_t c )
{
    size_t col, row;

    for( row = 0; row < r; row++ )
    {
        for( col = 0; col < c; col++ )
        {
            bar[ col ] += baz[ row ][ col ] * 5;
        }
    }
}


int main( void )
{
    int a1[ 5 ] = { 0 },
        b1[ 3 ][ 5 ] =
    {
        { 4, 5, 6, 7, 8 },
        { 1, 2, 9, 0, 3 },
        { 5, 10, 15, 20, 25 },
    };
    size_t x;

    foo( a1, b1, 3, 5 );
    
    for( x = 0; x < 5; x++ )
    {
        printf( "a1[ %d ] is %d. Expected: %d.\n",
        x, a1[ x ], (5 * ( b1[ 0 ][ x ] + b1[ 1 ][ x ] + b1[ 2 ][ x ]) )
        );
    }
    
    return 0;
}

Here's a helpful tip also: Never post code you've written when way too tired, the night before. (See above!)


Quzah.