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/*
Copyright 2024 Owain Davies
SPDX-License-Identifier: Apache-2.0 OR MIT
*/
use crate::{Arbi, BitCount};
impl Arbi {
/// Returns the base 10 logarithm of the number, rounded down.
///
/// # Panics
/// This function will panic if `self` is less than or equal to zero.
///
/// # Examples
/// ```
/// use arbi::Arbi;
/// let a = Arbi::from(10);
/// assert_eq!(a.ilog10(), 1);
/// ```
///
/// Nonpositive values panic:
/// ```should_panic
/// use arbi::Arbi;
/// let zero = Arbi::zero();
/// zero.ilog10();
/// ```
///
/// ```should_panic
/// use arbi::Arbi;
/// let neg_one = Arbi::neg_one();
/// neg_one.ilog10();
/// ```
pub fn ilog10(self) -> BitCount {
self.ilog(10)
}
/// Returns the base 10 logarithm of the number, rounded down.
///
/// The value of `self` will compare equal to the return value.
///
/// # Panics
/// This function will panic if `self` is less than or equal to zero.
///
/// # Examples
/// ```
/// use arbi::Arbi;
/// let mut a = Arbi::from(10);
/// assert_eq!(a.ilog10_mut(), 1);
/// assert_eq!(a, 1);
/// ```
///
/// Nonpositive values panic:
/// ```should_panic
/// use arbi::Arbi;
/// let mut zero = Arbi::zero();
/// zero.ilog10_mut();
/// ```
///
/// ```should_panic
/// use arbi::Arbi;
/// let mut minus_one = Arbi::neg_one();
/// minus_one.ilog10_mut();
/// ```
pub fn ilog10_mut(&mut self) -> BitCount {
self.ilog_mut(10)
}
/// Returns the base 10 logarithm of the number, rounded down.
///
/// # Panics
/// This function will panic if `self` is less than or equal to zero.
///
/// # Examples
/// ```
/// use arbi::Arbi;
/// let a = Arbi::from(10);
/// assert_eq!(a.ilog10_ref(), 1);
/// ```
///
/// Nonpositive values panic:
/// ```should_panic
/// use arbi::Arbi;
/// let zero = Arbi::zero();
/// zero.ilog10_ref();
/// ```
///
/// ```should_panic
/// use arbi::Arbi;
/// let minus_one = Arbi::neg_one();
/// minus_one.ilog10_ref();
/// ```
pub fn ilog10_ref(&self) -> BitCount {
self.ilog_ref(10)
}
}
#[cfg(test)]
mod tests {
use crate::uints::UnsignedUtilities;
use crate::util::test::{get_seedable_rng, get_uniform_die, Distribution};
use crate::{Arbi, BitCount, DDigit, Digit, QDigit};
#[test]
fn test_digit_boundaries() {
let a = Arbi::from(Digit::MAX);
assert_eq!(a.ilog10(), Digit::ilog10_(Digit::MAX) as BitCount);
let a = Arbi::from(Digit::MAX as DDigit + 1);
assert_eq!(
a.ilog10(),
DDigit::ilog10_(Digit::MAX as DDigit + 1) as BitCount
);
let a = Arbi::from(DDigit::MAX);
assert_eq!(a.ilog10(), DDigit::ilog10_(DDigit::MAX) as BitCount);
let a = Arbi::from(DDigit::MAX as QDigit + 1);
assert_eq!(
a.ilog10(),
QDigit::ilog10_(DDigit::MAX as QDigit + 1) as BitCount
);
}
#[test]
#[should_panic = "self must be positive: 0"]
fn test_zero() {
let a = Arbi::zero();
a.ilog10();
}
#[test]
#[should_panic = "self must be positive: -4"]
fn test_is_power_of_two_negative() {
let a = Arbi::from(-4);
a.ilog10();
}
#[test]
fn smoke() {
let (mut rng, _) = get_seedable_rng();
let die_digit = get_uniform_die(Digit::MIN, Digit::MAX);
let die_ddigit = get_uniform_die(Digit::MAX as DDigit + 1, DDigit::MAX);
let die_qdigit =
get_uniform_die(DDigit::MAX as QDigit + 1, QDigit::MAX);
for _ in 0..i16::MAX {
let r = die_digit.sample(&mut rng);
if r == 0 {
continue;
}
let a = Arbi::from(r);
assert_eq!(a.ilog10(), Digit::ilog10_(r) as BitCount);
let r = die_ddigit.sample(&mut rng);
let a = Arbi::from(r);
assert_eq!(a.ilog10(), DDigit::ilog10_(r) as BitCount);
let r = die_qdigit.sample(&mut rng);
let a = Arbi::from(r);
assert_eq!(a.ilog10(), QDigit::ilog10_(r) as BitCount);
}
}
}