#
# Compute a square root of a number
# and compare the result with standard sqrt(x) function
#
func main()
    while (0 == 0)      # Infinite loop
        print("Input a number (0 for the end): ");
        x = double(scan());
        if (x == 0.)
            break;
        endif
        y = squareRoot(x);
        println("squareRoot(x) = ", y);
        println("standard sqrt(x) = ", sqrt(x));
    endwhile
endfunc

# Compute a square root using Newton iterations
func squareRoot(a)
    println("    in squareRoot: a = ", a);
    if (a < 0.)
        println("    Incorrect argument");
        return 0.;
    endif

    EPS = 0.0000001;
    x = a;
    if (x < 1.)
        x = 1.;
    endif
    xPrev = x + 1e100;
    while (fabs(xPrev - x) > EPS)
        xPrev = x;
        x = (x + a/x) / 2.;
        println("    ", x);
    endwhile
    println("    in squareRoot: result = ", x);
    return x;
endfunc

# Starter
main();