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use core::f64;

/// Positive difference (f64)
///
/// Determines the positive difference between arguments, returning:
/// * x - y	if x > y, or
/// * +0	if x <= y, or
/// * NAN	if either argument is NAN.
///
/// A range error may occur.
#[cfg_attr(all(test, assert_no_panic), no_panic::no_panic)]
pub fn fdim(x: f64, y: f64) -> f64 {
    if x.is_nan() {
        x
    } else if y.is_nan() {
        y
    } else if x > y {
        x - y
    } else {
        0.0
    }
}