Matrix

[花颂]

hi guys, im doing a matrix addition using recursion. however it dosent seems to work.

//for (row=0; row<row_size; row++)
        //for (col=0; col<col_size; col++) 
            //mtxC[row][col] = mtxA[row][col] + mtxB[row][col]; using of for loop
            

// using of recursion

            for(counter ;counter<1; counter++)
            {
               store = col_size;            
            }  //col_size is the maximum size of the column eg. mtxA[][col_size]

            if(row_size==0 && col_size == 0)
            {
                     mtxC[row_size][col_size] = mtxA[row_size][col_size] + mtxB[row_size][col_size];
                     return mtxC,mtxA,mtxB,row_size,col_size;   
                // if both row_size and col_size reaches 0 which means it has comes to the end of the program and return all the values back to the place where its being called.
            }
            else
            {
            mtxC[row_size][col_size] = mtxA[row_size][col_size] + mtxB[row_size][col_size];
                        if(row_size!=0 && col_size==0) 
                        {
                        col_size=store;
                        row_size--;
                        col_size++;
                        }
            return sumMatrix(mtxC,mtxA,mtxB,row_size,col_size-1); 
            }

[laserlight]

How does it not work?

[花颂]

How does it not work?

u see, i cant find out which part of my coding went wrong.
assume the user enter a 2*2 array which is --> [0][0] [0][1]
[1][0] [1][1]
as a result col_size=1 and row_size=1
and it will start call up this function sumMatrix .
passing col_size value to store once only so it will not be affected by any changes that is about to make on col_size
subsequently the program will find its way down to the else and conduct addition:

 mtxC[row_size][col_size] = mtxA[row_size][col_size] + mtxB[row_size][col_size];

and return col_size-1 and other sumMatrix ​it will continues until
col_size reaches 0 and row_size will deduct 1 so it can proceed to another row in that array.
until the last where both row_size and col_size becomes 0 it will then return all the values back.

[AndiPersti]

for(counter ;counter<1; counter++)
{
    store = col_size;            
}

Do you understand that you are always assigning the same value to "store", thus making the for loop rather needless?

return mtxC,mtxA,mtxB,row_size,col_size;

In C, you can only return a single value from a function. In your case that's "col_size" because you are using the , (comma) operator in your expression.

Generally I don't think using recursion for adding to matrices is a good idea.

Bye, Andreas

[花颂]

thanks for replying....
counter was a global variable, its declared outside the function so the program will only go through it once.
i didnt know that c can only return 1 variable.... thanks for the information.
even removing the line i believe my algo should be working. can someone help to check whether my algo is correct or nt

[AndiPersti]

even removing the line i believe my algo should be working. can someone help to check whether my algo is correct or nt

Why don't you run the progam and check its output? You don't show us a complete program, so we can't test it.

And since I think that using a recursive algorithm for your problem isn't very smart I'm not really motivated to think through it.

Bye, Andreas