第一版

chanlun/src/utils/format.rs

@@ -0,0 +1,14 @@
+/// Format f64 with Python :g semantics — strip trailing zeros, no scientific notation for common values
+pub fn format_f64_g(value: f64) -> String {
+    if value.is_nan() {
+        return "nan".to_string();
+    }
+    if value.is_infinite() {
+        return if value > 0.0 { "inf".to_string() } else { "-inf".to_string() };
+    }
+
+    // Use high precision then trim trailing zeros
+    let s = format!("{:.15}", value);
+    let s = s.trim_end_matches('0');
+    s.trim_end_matches('.').to_string()
+}