If condition issue (C++)

Question

I have an issue with a piece of code in which I have an if statement that checks the diagonal elements of a complex array, and if they are (1,0) (meaning the real part is 1 and the imaginary part is 0) or very close to it then proceed; otherwise stop. But for some reason the operation always returns 0 although the elements are (0.999999, 0.000000), (1.000001, 0.000000), etc.

Here's the code I have:

for (i=1; i<=n; i++){
    if ((real(c[i][i][1]) < (1/100000)+1) && (imag(c[i][i][1]) < 1/100000) && (real(c[i][i][1]) > (-1/100000+1) && (imag(c[i][i][1]) > -1/100000)){
        cout<<"Operation continues...";
    }
    else
        return 0;
}

Thanks in advance.

Answer 1

This integer division yields 0 because the magnitude of the denominator is greater than that of the numerator:

1/100000

You need to use at least one floating point number here. For example

1.0/100000

Answer 2

1 / 100000 == 0 as it is integer division: you may write 0.00001 or 1. /100000.

BTW, you may write your loop:

constexpr double thresold = 0.00001;
for (i = 1; i <= n; i++) {
    if (std::abs(real(c[i][i][1]) - 1.) < thresold
        && std::abs(imag(c[i][i][1]) - 1.) < thresold) {
        cout << "Operation continues...";
    }
    else
        return 0;
}