Alex Crichton
GitHub
+224
@@ -408,3 +408,227 @@ pub fn pow(x: f64, y: f64) -> f64 {
|
||||
|
||||
return s * z;
|
||||
}
|
||||
|
||||
#[cfg(test)]
|
||||
mod tests {
|
||||
extern crate core;
|
||||
|
||||
use self::core::f64::consts::{E, PI};
|
||||
use self::core::f64::{EPSILON, INFINITY, MAX, MIN, MIN_POSITIVE, NAN, NEG_INFINITY};
|
||||
use super::pow;
|
||||
|
||||
const POS_ZERO: &[f64] = &[0.0];
|
||||
const NEG_ZERO: &[f64] = &[-0.0];
|
||||
const POS_ONE: &[f64] = &[1.0];
|
||||
const NEG_ONE: &[f64] = &[-1.0];
|
||||
const POS_FLOATS: &[f64] = &[99.0 / 70.0, E, PI];
|
||||
const NEG_FLOATS: &[f64] = &[-99.0 / 70.0, -E, -PI];
|
||||
const POS_SMALL_FLOATS: &[f64] = &[(1.0 / 2.0), MIN_POSITIVE, EPSILON];
|
||||
const NEG_SMALL_FLOATS: &[f64] = &[-(1.0 / 2.0), -MIN_POSITIVE, -EPSILON];
|
||||
const POS_EVENS: &[f64] = &[2.0, 6.0, 8.0, 10.0, 22.0, 100.0, MAX];
|
||||
const NEG_EVENS: &[f64] = &[MIN, -100.0, -22.0, -10.0, -8.0, -6.0, -2.0];
|
||||
const POS_ODDS: &[f64] = &[3.0, 7.0];
|
||||
const NEG_ODDS: &[f64] = &[-7.0, -3.0];
|
||||
const NANS: &[f64] = &[NAN];
|
||||
const POS_INF: &[f64] = &[INFINITY];
|
||||
const NEG_INF: &[f64] = &[NEG_INFINITY];
|
||||
|
||||
const ALL: &[&[f64]] = &[
|
||||
POS_ZERO,
|
||||
NEG_ZERO,
|
||||
NANS,
|
||||
NEG_SMALL_FLOATS,
|
||||
POS_SMALL_FLOATS,
|
||||
NEG_FLOATS,
|
||||
POS_FLOATS,
|
||||
NEG_EVENS,
|
||||
POS_EVENS,
|
||||
NEG_ODDS,
|
||||
POS_ODDS,
|
||||
NEG_INF,
|
||||
POS_INF,
|
||||
NEG_ONE,
|
||||
POS_ONE,
|
||||
];
|
||||
const POS: &[&[f64]] = &[POS_ZERO, POS_ODDS, POS_ONE, POS_FLOATS, POS_EVENS, POS_INF];
|
||||
const NEG: &[&[f64]] = &[NEG_ZERO, NEG_ODDS, NEG_ONE, NEG_FLOATS, NEG_EVENS, NEG_INF];
|
||||
|
||||
fn pow_test(base: f64, exponent: f64, expected: f64) {
|
||||
let res = pow(base, exponent);
|
||||
assert!(
|
||||
if expected.is_nan() {
|
||||
res.is_nan()
|
||||
} else {
|
||||
pow(base, exponent) == expected
|
||||
},
|
||||
"{} ** {} was {} instead of {}",
|
||||
base,
|
||||
exponent,
|
||||
res,
|
||||
expected
|
||||
);
|
||||
}
|
||||
|
||||
fn test_sets_as_base(sets: &[&[f64]], exponent: f64, expected: f64) {
|
||||
sets.iter()
|
||||
.for_each(|s| s.iter().for_each(|val| pow_test(*val, exponent, expected)));
|
||||
}
|
||||
|
||||
fn test_sets_as_exponent(base: f64, sets: &[&[f64]], expected: f64) {
|
||||
sets.iter()
|
||||
.for_each(|s| s.iter().for_each(|val| pow_test(base, *val, expected)));
|
||||
}
|
||||
|
||||
fn test_sets(sets: &[&[f64]], computed: &Fn(f64) -> f64, expected: &Fn(f64) -> f64) {
|
||||
sets.iter().for_each(|s| {
|
||||
s.iter().for_each(|val| {
|
||||
let exp = expected(*val);
|
||||
let res = computed(*val);
|
||||
|
||||
assert!(
|
||||
if exp.is_nan() {
|
||||
res.is_nan()
|
||||
} else {
|
||||
exp == res
|
||||
},
|
||||
"test for {} was {} instead of {}",
|
||||
val,
|
||||
res,
|
||||
exp
|
||||
);
|
||||
})
|
||||
});
|
||||
}
|
||||
|
||||
#[test]
|
||||
fn zero_as_exponent() {
|
||||
test_sets_as_base(ALL, 0.0, 1.0);
|
||||
test_sets_as_base(ALL, -0.0, 1.0);
|
||||
}
|
||||
|
||||
#[test]
|
||||
fn one_as_base() {
|
||||
test_sets_as_exponent(1.0, ALL, 1.0);
|
||||
}
|
||||
|
||||
#[test]
|
||||
fn nan_inputs() {
|
||||
// NAN as the base:
|
||||
// (NAN ^ anything *but 0* should be NAN)
|
||||
test_sets_as_exponent(NAN, &ALL[2..], NAN);
|
||||
|
||||
// NAN as the exponent:
|
||||
// (anything *but 1* ^ NAN should be NAN)
|
||||
test_sets_as_base(&ALL[..(ALL.len() - 2)], NAN, NAN);
|
||||
}
|
||||
|
||||
#[test]
|
||||
fn infinity_as_base() {
|
||||
// Positive Infinity as the base:
|
||||
// (+Infinity ^ positive anything but 0 and NAN should be +Infinity)
|
||||
test_sets_as_exponent(INFINITY, &POS[1..], INFINITY);
|
||||
|
||||
// (+Infinity ^ negative anything except 0 and NAN should be 0.0)
|
||||
test_sets_as_exponent(INFINITY, &NEG[1..], 0.0);
|
||||
|
||||
// Negative Infinity as the base:
|
||||
// (-Infinity ^ positive odd ints should be -Infinity)
|
||||
test_sets_as_exponent(NEG_INFINITY, &[POS_ODDS], NEG_INFINITY);
|
||||
|
||||
// (-Infinity ^ anything but odd ints should be == -0 ^ (-anything))
|
||||
// We can lump in pos/neg odd ints here because they don't seem to
|
||||
// cause panics (div by zero) in release mode (I think).
|
||||
test_sets(ALL, &|v: f64| pow(NEG_INFINITY, v), &|v: f64| pow(-0.0, -v));
|
||||
}
|
||||
|
||||
#[test]
|
||||
fn infinity_as_exponent() {
|
||||
// Positive/Negative base greater than 1:
|
||||
// (pos/neg > 1 ^ Infinity should be Infinity - note this excludes NAN as the base)
|
||||
test_sets_as_base(&ALL[5..(ALL.len() - 2)], INFINITY, INFINITY);
|
||||
|
||||
// (pos/neg > 1 ^ -Infinity should be 0.0)
|
||||
test_sets_as_base(&ALL[5..ALL.len() - 2], NEG_INFINITY, 0.0);
|
||||
|
||||
// Positive/Negative base less than 1:
|
||||
let base_below_one = &[POS_ZERO, NEG_ZERO, NEG_SMALL_FLOATS, POS_SMALL_FLOATS];
|
||||
|
||||
// (pos/neg < 1 ^ Infinity should be 0.0 - this also excludes NAN as the base)
|
||||
test_sets_as_base(base_below_one, INFINITY, 0.0);
|
||||
|
||||
// (pos/neg < 1 ^ -Infinity should be Infinity)
|
||||
test_sets_as_base(base_below_one, NEG_INFINITY, INFINITY);
|
||||
|
||||
// Positive/Negative 1 as the base:
|
||||
// (pos/neg 1 ^ Infinity should be 1)
|
||||
test_sets_as_base(&[NEG_ONE, POS_ONE], INFINITY, 1.0);
|
||||
|
||||
// (pos/neg 1 ^ -Infinity should be 1)
|
||||
test_sets_as_base(&[NEG_ONE, POS_ONE], NEG_INFINITY, 1.0);
|
||||
}
|
||||
|
||||
#[test]
|
||||
fn zero_as_base() {
|
||||
// Positive Zero as the base:
|
||||
// (+0 ^ anything positive but 0 and NAN should be +0)
|
||||
test_sets_as_exponent(0.0, &POS[1..], 0.0);
|
||||
|
||||
// (+0 ^ anything negative but 0 and NAN should be Infinity)
|
||||
// (this should panic because we're dividing by zero)
|
||||
test_sets_as_exponent(0.0, &NEG[1..], INFINITY);
|
||||
|
||||
// Negative Zero as the base:
|
||||
// (-0 ^ anything positive but 0, NAN, and odd ints should be +0)
|
||||
test_sets_as_exponent(-0.0, &POS[3..], 0.0);
|
||||
|
||||
// (-0 ^ anything negative but 0, NAN, and odd ints should be Infinity)
|
||||
// (should panic because of divide by zero)
|
||||
test_sets_as_exponent(-0.0, &NEG[3..], INFINITY);
|
||||
|
||||
// (-0 ^ positive odd ints should be -0)
|
||||
test_sets_as_exponent(-0.0, &[POS_ODDS], -0.0);
|
||||
|
||||
// (-0 ^ negative odd ints should be -Infinity)
|
||||
// (should panic because of divide by zero)
|
||||
test_sets_as_exponent(-0.0, &[NEG_ODDS], NEG_INFINITY);
|
||||
}
|
||||
|
||||
#[test]
|
||||
fn special_cases() {
|
||||
// One as the exponent:
|
||||
// (anything ^ 1 should be anything - i.e. the base)
|
||||
test_sets(ALL, &|v: f64| pow(v, 1.0), &|v: f64| v);
|
||||
|
||||
// Negative One as the exponent:
|
||||
// (anything ^ -1 should be 1/anything)
|
||||
test_sets(ALL, &|v: f64| pow(v, -1.0), &|v: f64| 1.0 / v);
|
||||
|
||||
// Factoring -1 out:
|
||||
// (negative anything ^ integer should be (-1 ^ integer) * (positive anything ^ integer))
|
||||
&[POS_ZERO, NEG_ZERO, POS_ONE, NEG_ONE, POS_EVENS, NEG_EVENS]
|
||||
.iter()
|
||||
.for_each(|int_set| {
|
||||
int_set.iter().for_each(|int| {
|
||||
test_sets(ALL, &|v: f64| pow(-v, *int), &|v: f64| {
|
||||
pow(-1.0, *int) * pow(v, *int)
|
||||
});
|
||||
})
|
||||
});
|
||||
|
||||
// Negative base (imaginary results):
|
||||
// (-anything except 0 and Infinity ^ non-integer should be NAN)
|
||||
&NEG[1..(NEG.len() - 1)].iter().for_each(|set| {
|
||||
set.iter().for_each(|val| {
|
||||
test_sets(&ALL[3..7], &|v: f64| pow(*val, v), &|_| NAN);
|
||||
})
|
||||
});
|
||||
}
|
||||
|
||||
#[test]
|
||||
fn normal_cases() {
|
||||
assert_eq!(pow(2.0, 20.0), (1 << 20) as f64);
|
||||
assert_eq!(pow(-1.0, 9.0), -1.0);
|
||||
assert!(pow(-1.0, 2.2).is_nan());
|
||||
assert!(pow(-1.0, -1.14).is_nan());
|
||||
}
|
||||
}
|
||||
|
||||
Reference in New Issue
Block a user