Math.cos, sin and tan returning inaccurate values in Java

Question

I am working on a calculator with a GUI in Java. The project is done, however the trigonometric functions do not work properly. This is the method for the cos function:

Answer 1

The value returned by cos is not inaccurate. When you input 90, and convert it to radian using the method Math.toRadians, the result is not exactly pi/2, and hence when you pass this non-exact value to cos it gives a non-exact value. Peek here to hear from the legend :-)

As for your situation, you need to round the result of cos. Take a look here

You could do something like this:

public void actionPerformed(ActionEvent evt) {
    input = Double.valueOf(Display.getText());
    ans = Math.cos(Math.toRadians(input));
    Display.setText(String.format("%.6f", ans));
}