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make exp_m1 and ln_1p examples more representative of use #77099

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Merged
bors merged 2 commits into from
Oct 31, 2020
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make exp_m1 and ln_1p examples more representative of use #77099

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37ce212
make exp_m1 examples more representative of use
tspiteri Sep 23, 2020
50d3ddc
make ln_1p examples more representative of use
tspiteri Sep 23, 2020
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18 changes: 10 additions & 8 deletions library/std/src/f32.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -719,12 +719,13 @@ impl f32 {
/// # Examples
///
/// ```
/// let x = 6.0f32;
/// let x = 1e-8_f32;
///
/// // e^(ln(6)) - 1
/// let abs_difference = (x.ln().exp_m1() - 5.0).abs();
/// // for very small x, e^x is approximately 1 + x + x^2 / 2
/// let approx = x + x * x / 2.0;
/// let abs_difference = (x.exp_m1() - approx).abs();
///
/// assert!(abs_difference <= f32::EPSILON);
/// assert!(abs_difference < 1e-10);
/// ```
#[must_use = "method returns a new number and does not mutate the original value"]
#[stable(feature = "rust1", since = "1.0.0")]
Expand All @@ -739,12 +740,13 @@ impl f32 {
/// # Examples
///
/// ```
/// let x = std::f32::consts::E - 1.0;
/// let x = 1e-8_f32;
///
/// // ln(1 + (e - 1)) == ln(e) == 1
/// let abs_difference = (x.ln_1p() - 1.0).abs();
/// // for very small x, ln(1 + x) is approximately x - x^2 / 2
/// let approx = x - x * x / 2.0;
/// let abs_difference = (x.ln_1p() - approx).abs();
///
/// assert!(abs_difference <= f32::EPSILON);
/// assert!(abs_difference < 1e-10);
/// ```
#[must_use = "method returns a new number and does not mutate the original value"]
#[stable(feature = "rust1", since = "1.0.0")]
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18 changes: 10 additions & 8 deletions library/std/src/f64.rs
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Expand Up @@ -721,12 +721,13 @@ impl f64 {
/// # Examples
///
/// ```
/// let x = 7.0_f64;
/// let x = 1e-16_f64;
///
/// // e^(ln(7)) - 1
/// let abs_difference = (x.ln().exp_m1() - 6.0).abs();
/// // for very small x, e^x is approximately 1 + x + x^2 / 2
/// let approx = x + x * x / 2.0;
/// let abs_difference = (x.exp_m1() - approx).abs();
///
/// assert!(abs_difference < 1e-10);
/// assert!(abs_difference < 1e-20);
/// ```
#[must_use = "method returns a new number and does not mutate the original value"]
#[stable(feature = "rust1", since = "1.0.0")]
Expand All @@ -741,12 +742,13 @@ impl f64 {
/// # Examples
///
/// ```
/// let x = std::f64::consts::E - 1.0;
/// let x = 1e-16_f64;
///
/// // ln(1 + (e - 1)) == ln(e) == 1
/// let abs_difference = (x.ln_1p() - 1.0).abs();
/// // for very small x, ln(1 + x) is approximately x - x^2 / 2
/// let approx = x - x * x / 2.0;
/// let abs_difference = (x.ln_1p() - approx).abs();
///
/// assert!(abs_difference < 1e-10);
/// assert!(abs_difference < 1e-20);
/// ```
#[must_use = "method returns a new number and does not mutate the original value"]
#[stable(feature = "rust1", since = "1.0.0")]
Expand Down