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// Copyright © 2024 Mikhail Hogrefe
//
// This file is part of Malachite.
//
// Malachite is free software: you can redistribute it and/or modify it under the terms of the GNU
// Lesser General Public License (LGPL) as published by the Free Software Foundation; either version
// 3 of the License, or (at your option) any later version. See <https://www.gnu.org/licenses/>.
use crate::InnerFloat::Finite;
use crate::{significand_bits, Float};
use core::cmp::Ordering::{self, *};
use malachite_base::num::arithmetic::traits::{
RoundToMultipleOfPowerOf2, RoundToMultipleOfPowerOf2Assign,
};
use malachite_base::num::basic::integers::PrimitiveInt;
use malachite_base::rounding_modes::RoundingMode::{self, *};
use malachite_nz::natural::Natural;
use malachite_nz::platform::Limb;
impl Float {
/// Gets the significand of a [`Float`], taking the [`Float`] by value.
///
/// The significand is the smallest positive integer which is some power of 2 times the
/// [`Float`], and whose number of significant bits is a multiple of the limb width. If the
/// [`Float`] is NaN, infinite, or zero, then `None` is returned.
///
/// # Worst-case complexity
/// Constant time and additional memory.
///
/// # Examples
/// ```
/// #[cfg(not(feature = "32_bit_limbs"))]
/// use malachite_base::num::arithmetic::traits::PowerOf2;
/// #[cfg(not(feature = "32_bit_limbs"))]
/// use malachite_base::num::basic::traits::One;
/// use malachite_base::num::basic::traits::{Infinity, NaN, Zero};
/// use malachite_float::Float;
/// #[cfg(not(feature = "32_bit_limbs"))]
/// use malachite_nz::natural::Natural;
///
/// assert_eq!(Float::NAN.to_significand(), None);
/// assert_eq!(Float::INFINITY.to_significand(), None);
/// assert_eq!(Float::ZERO.to_significand(), None);
///
/// #[cfg(not(feature = "32_bit_limbs"))]
/// {
/// assert_eq!(Float::ONE.to_significand(), Some(Natural::power_of_2(63)));
/// assert_eq!(
/// Float::from(std::f64::consts::PI).to_significand().unwrap(),
/// 14488038916154245120u64
/// );
/// }
/// ```
#[inline]
pub fn to_significand(&self) -> Option<Natural> {
match self {
Float(Finite { significand, .. }) => Some(significand.clone()),
_ => None,
}
}
/// Gets the significand of a [`Float`], taking the [`Float`] by reference.
///
/// The significand is the smallest positive integer which is some power of 2 times the
/// [`Float`], and whose number of significant bits is a multiple of the limb width. If the
/// [`Float`] is NaN, infinite, or zero, then `None` is returned.
///
/// # Worst-case complexity
/// Constant time and additional memory.
///
/// # Examples
/// ```
/// #[cfg(not(feature = "32_bit_limbs"))]
/// use malachite_base::num::arithmetic::traits::PowerOf2;
/// #[cfg(not(feature = "32_bit_limbs"))]
/// use malachite_base::num::basic::traits::One;
/// use malachite_base::num::basic::traits::{Infinity, NaN, Zero};
/// use malachite_float::Float;
/// #[cfg(not(feature = "32_bit_limbs"))]
/// use malachite_nz::natural::Natural;
///
/// assert_eq!(Float::NAN.into_significand(), None);
/// assert_eq!(Float::INFINITY.into_significand(), None);
/// assert_eq!(Float::ZERO.into_significand(), None);
///
/// #[cfg(not(feature = "32_bit_limbs"))]
/// {
/// assert_eq!(Float::ONE.into_significand(), Some(Natural::power_of_2(63)));
/// assert_eq!(
/// Float::from(std::f64::consts::PI)
/// .into_significand()
/// .unwrap(),
/// 14488038916154245120u64
/// );
/// }
/// ```
#[allow(clippy::missing_const_for_fn)] // destructor doesn't work with const
#[inline]
pub fn into_significand(self) -> Option<Natural> {
match self {
Float(Finite { significand, .. }) => Some(significand),
_ => None,
}
}
/// Returns a reference to the significand of a [`Float`].
///
/// The significand is the smallest positive integer which is some power of 2 times the
/// [`Float`], and whose number of significant bits is a multiple of the limb width. If the
/// [`Float`] is NaN, infinite, or zero, then `None` is returned.
///
/// # Worst-case complexity
/// Constant time and additional memory.
///
/// # Examples
/// ```
/// #[cfg(not(feature = "32_bit_limbs"))]
/// use malachite_base::num::arithmetic::traits::PowerOf2;
/// #[cfg(not(feature = "32_bit_limbs"))]
/// use malachite_base::num::basic::traits::One;
/// use malachite_base::num::basic::traits::{Infinity, NaN, Zero};
/// use malachite_float::Float;
/// #[cfg(not(feature = "32_bit_limbs"))]
/// use malachite_nz::natural::Natural;
///
/// assert_eq!(Float::NAN.significand_ref(), None);
/// assert_eq!(Float::INFINITY.significand_ref(), None);
/// assert_eq!(Float::ZERO.significand_ref(), None);
///
/// #[cfg(not(feature = "32_bit_limbs"))]
/// {
/// assert_eq!(
/// *Float::ONE.significand_ref().unwrap(),
/// Natural::power_of_2(63)
/// );
/// assert_eq!(
/// *Float::from(std::f64::consts::PI).significand_ref().unwrap(),
/// 14488038916154245120u64
/// );
/// }
/// ```
#[inline]
pub const fn significand_ref(&self) -> Option<&Natural> {
match self {
Float(Finite { significand, .. }) => Some(significand),
_ => None,
}
}
/// Returns a [`Float`]'s exponent.
///
/// $$
/// f(\text{NaN}) = f(\pm\infty) = f(\pm 0.0) = \text{None},
/// $$
///
/// and, if $x$ is finite and nonzero,
///
/// $$
/// f(x) = \operatorname{Some}(\lfloor \log_2 x \rfloor + 1).
/// $$
///
/// # Worst-case complexity
/// Constant time and additional memory.
///
/// # Examples
/// ```
/// use malachite_base::num::arithmetic::traits::PowerOf2;
/// use malachite_base::num::basic::traits::{Infinity, NaN, One, Zero};
/// use malachite_float::Float;
///
/// assert_eq!(Float::NAN.get_exponent(), None);
/// assert_eq!(Float::INFINITY.get_exponent(), None);
/// assert_eq!(Float::ZERO.get_exponent(), None);
///
/// assert_eq!(Float::ONE.get_exponent(), Some(1));
/// assert_eq!(Float::from(std::f64::consts::PI).get_exponent(), Some(2));
/// assert_eq!(Float::power_of_2(100u64).get_exponent(), Some(101));
/// assert_eq!(Float::power_of_2(-100i64).get_exponent(), Some(-99));
/// ```
#[inline]
pub const fn get_exponent(&self) -> Option<i64> {
match self {
Float(Finite { exponent, .. }) => Some(*exponent),
_ => None,
}
}
/// Returns a [`Float`]'s precision. The precision is a positive integer denoting how many of
/// the [`Float`]'s bits are significant.
///
/// Only [`Float`]s that are finite and nonzero have a precision. For other [`Float`]s, `None`
/// is returned.
///
/// # Worst-case complexity
/// Constant time and additional memory.
///
/// # Examples
/// ```
/// use malachite_base::num::basic::traits::{Infinity, NaN, One, Zero};
/// use malachite_float::Float;
///
/// assert_eq!(Float::NAN.get_prec(), None);
/// assert_eq!(Float::INFINITY.get_prec(), None);
/// assert_eq!(Float::ZERO.get_prec(), None);
///
/// assert_eq!(Float::ONE.get_prec(), Some(1));
/// assert_eq!(Float::one_prec(100).get_prec(), Some(100));
/// assert_eq!(Float::from(std::f64::consts::PI).get_prec(), Some(53));
/// ```
#[inline]
pub const fn get_prec(&self) -> Option<u64> {
match self {
Float(Finite { precision, .. }) => Some(*precision),
_ => None,
}
}
/// Returns the minimum precision necessary to represent the given [`Float`]'s value.
///
/// For example, `Float:one_prec(100)` has a precision of 100, but its minimum precision is 1,
/// because that's all that's necessary to represent the value 1.
///
/// The minimum precision is always less than or equal to the actual precision.
///
/// Only [`Float`]s that are finite and nonzero have a minimum precision. For other [`Float`]s,
/// `None` is returned.
///
/// # Worst-case complexity
/// Constant time and additional memory.
///
/// # Examples
/// ```
/// use malachite_base::num::basic::traits::{Infinity, NaN, One, Zero};
/// use malachite_float::Float;
///
/// assert_eq!(Float::NAN.get_min_prec(), None);
/// assert_eq!(Float::INFINITY.get_min_prec(), None);
/// assert_eq!(Float::ZERO.get_min_prec(), None);
///
/// assert_eq!(Float::ONE.get_min_prec(), Some(1));
/// assert_eq!(Float::one_prec(100).get_min_prec(), Some(1));
/// assert_eq!(Float::from(std::f64::consts::PI).get_min_prec(), Some(50));
/// ```
pub fn get_min_prec(&self) -> Option<u64> {
match self {
Float(Finite { significand, .. }) => {
Some(significand_bits(significand) - significand.trailing_zeros().unwrap())
}
_ => None,
}
}
/// Changes a [`Float`]'s precision. If the precision decreases, rounding may be necessary, and
/// will use the provided [`RoundingMode`].
///
/// Returns an [`Ordering`], indicating whether the final value is less than, greater than, or
/// equal to the original value.
///
/// # Worst-case complexity
/// $T(n) = O(n)$
///
/// $M(n) = O(n)$
///
/// where $T$ is time, $M$ is additional memory, and $n$ is `prec`.
///
/// # Panics
/// Panics if `prec` is zero or if `rm` is [`Exact`] but setting the desired precision requires
/// rounding.
///
/// # Examples
/// ```
/// use malachite_base::rounding_modes::RoundingMode::*;
/// use malachite_float::Float;
/// use std::cmp::Ordering::*;
///
/// let original_x = Float::from(1.0f64 / 3.0);
/// assert_eq!(original_x.to_string(), "0.33333333333333331");
/// assert_eq!(original_x.get_prec(), Some(53));
///
/// let mut x = original_x.clone();
/// assert_eq!(x.set_prec_round(100, Exact), Equal);
/// assert_eq!(x.to_string(), "0.3333333333333333148296162562474");
/// assert_eq!(x.get_prec(), Some(100));
///
/// let mut x = original_x.clone();
/// assert_eq!(x.set_prec_round(10, Floor), Less);
/// assert_eq!(x.to_string(), "0.333");
/// assert_eq!(x.get_prec(), Some(10));
///
/// let mut x = original_x.clone();
/// assert_eq!(x.set_prec_round(10, Ceiling), Greater);
/// assert_eq!(x.to_string(), "0.3335");
/// assert_eq!(x.get_prec(), Some(10));
/// ```
pub fn set_prec_round(&mut self, prec: u64, rm: RoundingMode) -> Ordering {
assert_ne!(prec, 0);
match self {
Float(Finite {
sign,
exponent,
precision,
significand,
}) => {
let target_bits = prec
.round_to_multiple_of_power_of_2(Limb::LOG_WIDTH, Ceiling)
.0;
let significant_bits = significand_bits(significand);
let o;
if target_bits > significant_bits {
*significand <<= target_bits - significant_bits;
o = Equal;
} else {
let limb_count = significand.limb_count();
let abs_rm = if *sign { rm } else { -rm };
o = significand
.round_to_multiple_of_power_of_2_assign(significant_bits - prec, abs_rm);
if significand.limb_count() > limb_count {
*significand >>= 1;
*exponent = exponent.checked_add(1).unwrap();
}
*significand >>= significant_bits - target_bits;
}
*precision = prec;
if *sign {
o
} else {
o.reverse()
}
}
_ => Equal,
}
}
/// Changes a [`Float`]'s precision. If the precision decreases, rounding may be necessary, and
/// [`Nearest`] will be used.
///
/// Returns an [`Ordering`], indicating whether the final value is less than, greater than, or
/// equal to the original value.
///
/// To use a different rounding mode, try [`Float::set_prec_round`].
///
/// # Worst-case complexity
/// $T(n) = O(n)$
///
/// $M(n) = O(n)$
///
/// where $T$ is time, $M$ is additional memory, and $n$ is `prec`.
///
/// # Examples
/// ```
/// use malachite_float::Float;
/// use std::cmp::Ordering::*;
///
/// let original_x = Float::from(1.0f64 / 3.0);
/// assert_eq!(original_x.to_string(), "0.33333333333333331");
/// assert_eq!(original_x.get_prec(), Some(53));
///
/// let mut x = original_x.clone();
/// assert_eq!(x.set_prec(100), Equal);
/// assert_eq!(x.to_string(), "0.3333333333333333148296162562474");
/// assert_eq!(x.get_prec(), Some(100));
///
/// let mut x = original_x.clone();
/// assert_eq!(x.set_prec(10), Greater);
/// assert_eq!(x.to_string(), "0.3335");
/// assert_eq!(x.get_prec(), Some(10));
/// ```
#[inline]
pub fn set_prec(&mut self, p: u64) -> Ordering {
self.set_prec_round(p, Nearest)
}
}