rust: Expose g3

crates/ekore/src/harmonics/cache.rs

@@ -3,7 +3,7 @@
 use hashbrown::HashMap;
 use num::{complex::Complex, Zero};
 
-use crate::harmonics::{w1, w2, w3};
+use crate::harmonics::{g_functions, w1, w2, w3};
 
 #[cfg_attr(doc, katexit::katexit)]
 /// List of available elements.
@@ -25,6 +25,8 @@ pub enum K {
     S2mh,
     /// $S_3((N-1)/2)$
     S3mh,
+    /// $g_3(N)$
+    G3,
 }
 
 /// Hold all cached values.
@@ -61,6 +63,7 @@ impl Cache {
             K::S1mh => w1::S1((self.n - 1.) / 2.),
             K::S2mh => w2::S2((self.n - 1.) / 2.),
             K::S3mh => w3::S3((self.n - 1.) / 2.),
+            K::G3 => g_functions::g3(self.n, self.get(K::S1)),
         };
         // insert
         self.m.insert(k, val);

crates/ekore/src/harmonics/g_functions.rs

@@ -1,3 +1,5 @@
+//! Auxilary functions for harmonics sums of weight = 3,4.
+
 use crate::constants::ZETA2;
 use crate::harmonics::cache::recursive_harmonic_sum as s;
 use num::{complex::Complex, Zero};
@@ -10,7 +12,7 @@ use num::{complex::Complex, Zero};
 ///
 /// We use the name from [[MuselliPhD]][crate::bib::MuselliPhD], but not his implementation - rather we use the
 /// Pegasus [[Vogt:2004ns]][crate::bib::Vogt2004ns] implementation.
-pub fn mellin_g3(N: Complex<f64>, S1: Complex<f64>) -> Complex<f64> {
+pub fn g3(N: Complex<f64>, S1: Complex<f64>) -> Complex<f64> {
     const CS: [f64; 7] = [
         1.0000e0, -0.9992e0, 0.9851e0, -0.9005e0, 0.6621e0, -0.3174e0, 0.0699e0,
     ];
@@ -24,7 +26,7 @@ pub fn mellin_g3(N: Complex<f64>, S1: Complex<f64>) -> Complex<f64> {
 
 #[cfg(test)]
 mod tests {
-    use crate::harmonics::g_functions::mellin_g3;
+    use crate::harmonics::g_functions::g3;
     use crate::harmonics::w1;
     use crate::{assert_approx_eq_cmplx, cmplx};
     use num::complex::Complex;
@@ -42,7 +44,7 @@ mod tests {
             let n = *it.1;
             let s1 = w1::S1(n);
             let refval = REFVALS[it.0];
-            let g3 = mellin_g3(n, s1);
+            let g3 = g3(n, s1);
             assert_approx_eq_cmplx![f64, g3, refval, epsilon = 1e-6];
         }
     }

crates/ekore/src/harmonics/w1.rs

@@ -1,3 +1,4 @@
+//! Harmonic sums of weight 1.
 use num::complex::Complex;
 
 use crate::harmonics::polygamma::cern_polygamma;

crates/ekore/src/harmonics/w2.rs

@@ -1,3 +1,4 @@
+//! Harmonic sums of weight 2.
 use num::complex::Complex;
 
 use crate::constants::ZETA2;

crates/ekore/src/harmonics/w3.rs

@@ -1,3 +1,4 @@
+//! Harmonic sums of weight 3.
 use num::complex::Complex;
 
 use crate::constants::ZETA3;