Ver 0.4.4

- Update dependencies (#48)
- Export erfcx from public API
- Add max iteration guard to gser/gcf to prevent potential infinite loops
- Add input validation to beta()
- Clarify misleading comment in faddeeva.rs

Author: Axect

Cargo.lock

@@ -1,6 +1,6 @@
 [package]
 name = "puruspe"
-version = "0.4.3"
+version = "0.4.4"
 authors = ["Axect <axect@outlook.kr>"]
 description = "Pure Rust Special function library"
 edition = "2018"

Cargo.toml

@@ -20,7 +20,7 @@ Add this to your `Cargo.toml`:
 
 ```toml
 [dependencies]
-puruspe = "0.4.3"
+puruspe = "0.4.4"
 ```
 
 ## Example

README.md

@@ -1,3 +1,12 @@
+# Ver 0.4.4 (2026-03-17)
+
+- Update dependencies ([#48](https://github.com/Axect/puruspe/pull/48))
+  - Thanks to [**JSorngard**](https://github.com/JSorngard)
+- Export `erfcx` from public API
+- Add max iteration guard to `gser`/`gcf` to prevent potential infinite loops
+- Add input validation to `beta()`
+- Clarify misleading comment in faddeeva.rs
+
 # Ver 0.4.3 (2025-11-12)
 
 - Implement the Gamma function by Toshio Fukushima with very low relative error

RELEASES.md

@@ -26,7 +26,12 @@ const SWITCH: usize = 3000;
 /// # Returns
 ///
 /// The value of the beta function $B(z,w)$
+///
+/// # Panics
+///
+/// Panics if `z` ≤ 0 or `w` ≤ 0.
 pub fn beta(z: f64, w: f64) -> f64 {
+    assert!(z > 0f64 && w > 0f64, "Bad args in beta: z and w must be positive");
     (ln_gamma(z) + ln_gamma(w) - ln_gamma(z + w)).exp()
 }
 

src/beta.rs

@@ -243,7 +243,7 @@ pub fn faddeeva(re: f64, im: f64) -> (f64, f64) {
     let t_next = TAYLOR_COEFFS[idx + 1];
     let dz = c64::new(xabs - t, yabs - t_next);
 
-    // Something is wrong here...
+    // Horner's method: loop stops at k=1 (not k=0), matching libcerf
     let nk = TILES[i_tile + 1];
     res = c64::new(
         TAYLOR_COEFFS[(idx as isize + 2 * nk as isize) as usize],

src/faddeeva.rs

@@ -283,11 +283,12 @@ pub fn gammq(a: f64, x: f64) -> f64 {
 
 /// Series expansion
 fn gser(a: f64, x: f64) -> f64 {
+    const MAXIT: usize = 10_000;
     let gln = ln_gamma(a);
     let mut ap = a;
     let mut del = 1f64 / a;
     let mut sum = 1f64 / a;
-    loop {
+    for _ in 0..MAXIT {
         ap += 1f64;
         del *= x / ap;
         sum += del;
@@ -305,18 +306,28 @@ fn gser(a: f64, x: f64) -> f64 {
             return sum * log_result.exp();
         }
     }
+    // Return best estimate if not fully converged
+    let log_result = -x + a * x.ln() - gln;
+    if log_result > 700.0 {
+        sum * f64::INFINITY
+    } else if log_result < -700.0 {
+        0.0
+    } else {
+        sum * log_result.exp()
+    }
 }
 
 /// Continued Fraction
 fn gcf(a: f64, x: f64) -> f64 {
+    const MAXIT: usize = 10_000;
     let gln = ln_gamma(a);
     let mut b = x + 1f64 - a;
     let mut c = 1f64 / FPMIN;
     let mut d = 1f64 / b;
     let mut h = d;
     let mut an: f64;
-    for i in 1.. {
-        an = -i as f64 * (i as f64 - a);
+    for i in 1..=MAXIT {
+        an = -(i as f64) * (i as f64 - a);
         b += 2f64;
         d = an * d + b;
         if d.abs() < FPMIN {

src/gamma.rs

@@ -16,7 +16,7 @@ pub mod beta;
 pub use beta::{beta, betai, invbetai};
 
 pub mod error;
-pub use error::{erf, erfc, inverf, inverfc};
+pub use error::{erf, erfc, erfcx, inverf, inverfc};
 
 pub mod dawson;
 pub use dawson::dawson;