Symetricc / anti symetricc matrix

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Hey guys , i want to write a function (one function) that tells if a nxn matrix is symmetric 'or' anti symmetric , i had problems with 'return' . this would be easy if it was in 2 different functions but it's just One in this case . can you please help ? thanks . ( C language )

What I have tried:

C

int vrf_sym_anti(const int  **M,const int  n);
int vrf_sym_anti(const int  **M,const int  n)
{
    int i,j,c=0,sym=0,antisym=0;
    for(i=0; i<n; i++)
        for(j=0; j<n; j++)
        {
            if(M[i][j]!=(M[j][i] || -M[j][i]))
               c++;
               else
                if(M[i][j]==M[j][i])
                sym++;
                else
                    if((M[i][j]==-M[j][i]) && M[i][i]==0)
                    antisym++;
        }
 if(c!=0)
    return 0; ///Ni sym ni antsym
 if(sym==(pow(n,2)-n)/2)
    return 1; ///sym
 if(antisym==(pow(n,2)+2)/2)
    return -1; ///antiym
}

Posted 30-Dec-17 10:04am

Outh_Mane

Updated 31-Dec-17 2:56am

Patrice T

v3

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OriginalGriff 31-Dec-17 4:20am

What problem?

And do yourself a favour: sort out your indentation!

Outh_Mane 31-Dec-17 7:46am

It doesnt work , it always shows it's not sym or antisym

OriginalGriff 31-Dec-17 7:51am

And?
What have you done to find out why?

Outh_Mane 31-Dec-17 8:54am

i type in matrixs that i know their types , i use this function in a full code . but it's okay i found a solution to this probleme . i changed the conditions in "if" and it gave me the correct answer

3 solutions

Solution 3

i did this and it works

int vrf_sym_anti(const int **M,const int n);
int vrf_sym_anti(const int **M,const int n)
{
int i,j,sym=0,antisym=0;
for(i=0; i<n; i++)
for(j=0; j<n; j++)
{
if(M[i][j]==M[j][i])
sym++;
else
if((M[i][j]==-M[j][i])&&(M[i][i]==0))
antisym++;
}
if(sym==n*n)
return 1; ///sym
else
if(antisym==(n*n)-n)
return -1; ///antiym
else
return 0; ///Ni sym ni antsym
}

Posted 31-Dec-17 2:56am

Outh_Mane

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Richard MacCutchan · Accepted Answer · 2017-12-30T22:33:00

You have an incomplete if clause at the end, which the compiler does not like:

C++

 if(c!=0)
    return 0; ///Ni sym ni antsym
 if(sym==(pow(n,2)-n)/2)
    return 1; ///sym
 if(antisym==(pow(n,2)+2)/2)
    return -1; ///antiym
// OK, now what to do if antisym is not equal to that expression?
// you need a final return statement here
// or better still use if ... else if ... else if ... else ...

OriginalGriff · Accepted Answer · 2017-12-31T01:55:00

This is just a guess, but ...
Replace this:

if(M[i][j]!=(M[j][i] || -M[j][i]))

With this:

if(M[i][j] != M[j][i] && M[i][j] != -M[j][i]))

when you OR two integers using || use treat them as boolean values: so

(M[j][i] || -M[j][i])

Will return true or false - and probably doesn't match your cell contents.

Symetricc / anti symetricc matrix

3 solutions

Solution 1

Solution 2

Solution 3

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