Make Quantile work for no_std via libm

This requires the new `libm` feature, which is enabled by default.

This is a breaking change.

Cargo.toml

@@ -15,7 +15,9 @@ include = ["src/**/*", "benches/*", "LICENSE-*", "README.md"]
 [features]
 serde1 = ["serde", "serde_derive", "serde-big-array"]
 nightly = []
-std = ["easy-cast"]
+std = ["easy-cast/std"]
+libm = ["easy-cast/libm"]
+default = ["libm"]
 
 [[bench]]
 harness = false
@@ -32,7 +34,7 @@ name = "kurtosis"
 [dependencies]
 num-traits = { version = "0.2", default-features = false }
 float-ord = "0.2"
-easy-cast = { version = "0.2", optional = true }
+easy-cast = { version = "0.3", default-features = false, optional = true }
 serde = { version = "1", features = ["derive"], optional = true }
 serde_derive = { version = "1", optional = true }
 serde-big-array = { version = "0.3.0", optional = true }

README.md

@@ -30,9 +30,12 @@ This crate works without `std`.
 
 ## Crate features
 
-The following optional features are available:
+The following features are available:
 
-* `std` enables `Quantile` (`std` is required for floating point functions).
+* `libm` enables `Quantile` (using floating point functions provided by `libm`).
+ This is enabled by default. If the `std` feature is also enabled, `std` is
+ preferred over `libm`.
+* `std` enables `Quantile` (using floating point functions provided by `std`).
 * `serde1` enables serialization, via Serde version 1.
 * `rayon` enables support for `rayon::iter::FromParallelIterator`.
 * `nightly` enables the use of const generics for a histogram implementation

src/lib.rs

@@ -102,7 +102,7 @@
 #[macro_use] mod moments;
 mod weighted_mean;
 mod minmax;
-#[cfg(feature = "std")]
+#[cfg(any(feature = "std", feature = "libm"))]
 mod quantile;
 mod traits;
 #[macro_use] mod histogram;
@@ -112,7 +112,7 @@ pub mod histogram_const;
 pub use crate::moments::{Mean, Variance, Skewness, Kurtosis, MeanWithError};
 pub use crate::weighted_mean::{WeightedMean, WeightedMeanWithError};
 pub use crate::minmax::{Min, Max};
-#[cfg(feature = "std")]
+#[cfg(any(feature = "std", feature = "libm"))]
 pub use crate::quantile::Quantile;
 pub use crate::traits::{Estimate, Merge, Histogram};
 pub use crate::histogram::{InvalidRangeError, SampleOutOfRangeError};

tests/integration/macros.rs

@@ -49,7 +49,7 @@ fn concatenate_moments_max() {
  assert_eq!(e.max(), 5.0);
 }
 
-#[cfg(feature = "std")]
+#[cfg(any(feature = "std", feature = "libm"))]
 #[test]
 fn concatenate_moments_quantile() {
  use average::{Variance, Quantile};

tests/integration/main.rs

@@ -11,7 +11,7 @@ mod mean;
 mod min;
 mod moments;
 mod proptest;
-#[cfg(feature = "std")]
+#[cfg(any(feature = "std", feature = "libm"))]
 mod quantile;
 mod random;
 mod skewness;