How do I pass and manipulate the arguments of a matrix into the function using pointers?

Question

i have managed to send the arguments using pointers and matrix size inside of main like so:

int main()
{

    swap(*(matrix+0)+1, 0, 1, *(matrix+3)+2, 3, 2);
}

my question really is, how do I swap out these two values of the matrix using the following function?

this is what I have so far in regards to the function:

void swap(float **a, int i, int j, float **b, int x, int y)
{

    float temp;
    temp = *(a+i)+j;
    *(a+i)+j = *(b+x)+y;
    *(b+x)+y = temp;
}

The errors are: incomaptible types when assigning to type 'float' from type 'float *', and lvalue required as left operand of assignment.