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add min_pos_value constant for floats #13735

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Merged
merged 1 commit into from
Apr 25, 2014
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add min_pos_value constant for floats #13735

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16 changes: 11 additions & 5 deletions src/libstd/num/f32.rs
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Expand Up @@ -71,9 +71,11 @@ pub static DIGITS: uint = 6u;

pub static EPSILON: f32 = 1.19209290e-07_f32;

/// Minimum normalized f32 value
pub static MIN_VALUE: f32 = 1.17549435e-38_f32;
/// Maximum f32 value
/// Smallest finite f32 value
pub static MIN_VALUE: f32 = -3.40282347e+38_f32;
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Is there a different but still reasonable name for this? It may be confusing for someone who's used to C's weird definition and tries to use this constant without looking at the value.

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This doesn't shock me since Rust tries to fix the C/C++ legacy in various domains... plus I would expect a newcomer to at least lookup the function name/doc on rustdoc.

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C++11 introduced numeric_limits::lowest, but that's an ugly backwards compatibility workaround. So long as we document this, I think it is good to get this right from the start.

/// Smallest positive, normalized f32 value
pub static MIN_POS_VALUE: f32 = 1.17549435e-38_f32;
/// Largest finite f32 value
pub static MAX_VALUE: f32 = 3.40282347e+38_f32;

pub static MIN_EXP: int = -125;
Expand All @@ -90,8 +92,9 @@ pub static NEG_INFINITY: f32 = -1.0_f32/0.0_f32;
pub mod consts {
// FIXME: replace with mathematical constants from cmath.

// FIXME(#11621): These constants should be deprecated once CTFE is
// implemented in favour of calling their respective functions in `Float`.
// FIXME(#5527): These constants should be deprecated once associated
// constants are implemented in favour of referencing the respective members
// of `Float`.

/// Archimedes' constant
pub static PI: f32 = 3.14159265358979323846264338327950288_f32;
Expand Down Expand Up @@ -342,6 +345,9 @@ impl Float for f32 {
#[inline]
fn max_10_exp(_: Option<f32>) -> int { MAX_10_EXP }

#[inline]
fn min_pos_value(_: Option<f32>) -> f32 { MIN_POS_VALUE }

/// Constructs a floating point number by multiplying `x` by 2 raised to the
/// power of `exp`
#[inline]
Expand Down
35 changes: 21 additions & 14 deletions src/libstd/num/f64.rs
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Expand Up @@ -73,8 +73,9 @@ mod cmath {
}
}

// FIXME(#11621): These constants should be deprecated once CTFE is implemented
// in favour of calling their respective functions in `Bounded` and `Float`.
// FIXME(#5527): These constants should be deprecated once associated
// constants are implemented in favour of referencing the respective
// members of `Bounded` and `Float`.

pub static RADIX: uint = 2u;

Expand All @@ -83,9 +84,11 @@ pub static DIGITS: uint = 15u;

pub static EPSILON: f64 = 2.2204460492503131e-16_f64;

/// Minimum normalized f64 value
pub static MIN_VALUE: f64 = 2.2250738585072014e-308_f64;
/// Maximum f64 value
/// Smallest finite f64 value
pub static MIN_VALUE: f64 = -1.7976931348623157e+308_f64;
/// Smallest positive, normalized f64 value
pub static MIN_POS_VALUE: f64 = 2.2250738585072014e-308_f64;
/// Largest finite f64 value
pub static MAX_VALUE: f64 = 1.7976931348623157e+308_f64;

pub static MIN_EXP: int = -1021;
Expand All @@ -104,8 +107,9 @@ pub static NEG_INFINITY: f64 = -1.0_f64/0.0_f64;
pub mod consts {
// FIXME: replace with mathematical constants from cmath.

// FIXME(#11621): These constants should be deprecated once CTFE is
// implemented in favour of calling their respective functions in `Float`.
// FIXME(#5527): These constants should be deprecated once associated
// constants are implemented in favour of referencing the respective members
// of `Float`.

/// Archimedes' constant
pub static PI: f64 = 3.14159265358979323846264338327950288_f64;
Expand Down Expand Up @@ -330,25 +334,28 @@ impl Float for f64 {
}

#[inline]
fn mantissa_digits(_: Option<f64>) -> uint { 53 }
fn mantissa_digits(_: Option<f64>) -> uint { MANTISSA_DIGITS }

#[inline]
fn digits(_: Option<f64>) -> uint { 15 }
fn digits(_: Option<f64>) -> uint { DIGITS }

#[inline]
fn epsilon() -> f64 { 2.2204460492503131e-16 }
fn epsilon() -> f64 { EPSILON }

#[inline]
fn min_exp(_: Option<f64>) -> int { -1021 }
fn min_exp(_: Option<f64>) -> int { MIN_EXP }

#[inline]
fn max_exp(_: Option<f64>) -> int { 1024 }
fn max_exp(_: Option<f64>) -> int { MAX_EXP }

#[inline]
fn min_10_exp(_: Option<f64>) -> int { -307 }
fn min_10_exp(_: Option<f64>) -> int { MIN_10_EXP }

#[inline]
fn max_10_exp(_: Option<f64>) -> int { 308 }
fn max_10_exp(_: Option<f64>) -> int { MAX_10_EXP }

#[inline]
fn min_pos_value(_: Option<f64>) -> f64 { MIN_POS_VALUE }

/// Constructs a floating point number by multiplying `x` by 2 raised to the
/// power of `exp`
Expand Down
8 changes: 8 additions & 0 deletions src/libstd/num/mod.rs
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Expand Up @@ -190,7 +190,9 @@ pub fn pow<T: One + Mul<T, T>>(mut base: T, mut exp: uint) -> T {
/// Numbers which have upper and lower bounds
pub trait Bounded {
// FIXME (#5527): These should be associated constants
/// returns the smallest finite number this type can represent
fn min_value() -> Self;
/// returns the largest finite number this type can represent
fn max_value() -> Self;
}

Expand Down Expand Up @@ -356,6 +358,8 @@ pub trait Float: Signed + Primitive {
/// Returns the category that this number falls into.
fn classify(self) -> FPCategory;

// FIXME (#5527): These should be associated constants

/// Returns the number of binary digits of mantissa that this type supports.
fn mantissa_digits(unused_self: Option<Self>) -> uint;
/// Returns the number of base-10 digits of precision that this type supports.
Expand All @@ -370,6 +374,8 @@ pub trait Float: Signed + Primitive {
fn min_10_exp(unused_self: Option<Self>) -> int;
/// Returns the maximum base-10 exponent that this type can represent.
fn max_10_exp(unused_self: Option<Self>) -> int;
/// Returns the smallest normalized positive number that this type can represent.
fn min_pos_value(unused_self: Option<Self>) -> Self;

/// Constructs a floating point number created by multiplying `x` by 2
/// raised to the power of `exp`.
Expand Down Expand Up @@ -434,6 +440,8 @@ pub trait Float: Signed + Primitive {
/// legs of length `x` and `y`.
fn hypot(self, other: Self) -> Self;

// FIXME (#5527): These should be associated constants

/// Archimedes' constant.
fn pi() -> Self;
/// 2.0 * pi.
Expand Down