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use core::num::flt2dec::estimator::*;
#[test]
fn test_estimate_scaling_factor() {
macro_rules! assert_almost_eq {
($actual:expr, $expected:expr) => {{
let actual = $actual;
let expected = $expected;
println!(
"{} - {} = {} - {} = {}",
stringify!($expected),
stringify!($actual),
expected,
actual,
expected - actual
);
assert!(
expected == actual || expected == actual + 1,
"expected {}, actual {}",
expected,
actual
);
}};
}
assert_almost_eq!(estimate_scaling_factor(1, 0), 0);
assert_almost_eq!(estimate_scaling_factor(2, 0), 1);
assert_almost_eq!(estimate_scaling_factor(10, 0), 1);
assert_almost_eq!(estimate_scaling_factor(11, 0), 2);
assert_almost_eq!(estimate_scaling_factor(100, 0), 2);
assert_almost_eq!(estimate_scaling_factor(101, 0), 3);
assert_almost_eq!(estimate_scaling_factor(10000000000000000000, 0), 19);
assert_almost_eq!(estimate_scaling_factor(10000000000000000001, 0), 20);
// 1/2^20 = 0.00000095367...
assert_almost_eq!(estimate_scaling_factor(1 * 1048576 / 1000000, -20), -6);
assert_almost_eq!(estimate_scaling_factor(1 * 1048576 / 1000000 + 1, -20), -5);
assert_almost_eq!(estimate_scaling_factor(10 * 1048576 / 1000000, -20), -5);
assert_almost_eq!(estimate_scaling_factor(10 * 1048576 / 1000000 + 1, -20), -4);
assert_almost_eq!(estimate_scaling_factor(100 * 1048576 / 1000000, -20), -4);
assert_almost_eq!(estimate_scaling_factor(100 * 1048576 / 1000000 + 1, -20), -3);
assert_almost_eq!(estimate_scaling_factor(1048575, -20), 0);
assert_almost_eq!(estimate_scaling_factor(1048576, -20), 0);
assert_almost_eq!(estimate_scaling_factor(1048577, -20), 1);
assert_almost_eq!(estimate_scaling_factor(10485759999999999999, -20), 13);
assert_almost_eq!(estimate_scaling_factor(10485760000000000000, -20), 13);
assert_almost_eq!(estimate_scaling_factor(10485760000000000001, -20), 14);
// extreme values:
// 2^-1074 = 4.94065... * 10^-324
// (2^53-1) * 2^971 = 1.79763... * 10^308
assert_almost_eq!(estimate_scaling_factor(1, -1074), -323);
assert_almost_eq!(estimate_scaling_factor(0x1fffffffffffff, 971), 309);
// Miri is too slow
let step = if cfg!(miri) { 37 } else { 1 };
for i in (-1074..972).step_by(step) {
let expected = super::ldexp_f64(1.0, i).log10().ceil();
assert_almost_eq!(estimate_scaling_factor(1, i as i16), expected as i16);
}
}
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