Review fixes for #2393, #2394, #2397 and #2399

- PMT: take rate / m first so (pv + fv) / m can't overflow for a tiny rate (PMT(1e-300,10,1e12)).
- Keytips probe: an empty params object keys like no params.
- Number Stored as Text check reads the same accounting parentheses as typed entry.
- Lookups: a NaN number falls back to the general comparison instead of comparing equal.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

crates/core/src/parse.rs

@@ -54,8 +54,10 @@ pub fn parse_number_text_in(s: &str, sys: DateSystem) -> Option<f64> {
 /// fractions kept as text are not flagged, as in Excel.
 pub fn number_stored_as_text(s: &str) -> Option<f64> {
     let t = s.trim();
-    match t.strip_prefix('(').and_then(|x| x.strip_suffix(')')) {
-        Some(inner) => parse_plain(inner.trim()).map(|(n, _)| -n),
+    // The same parentheses typed entry reads, accounting forms included: `$(5)`, `(5)%`.
+    match parenthesized(t) {
+        Some(inner) if inner.strip_prefix('$').map_or(inner.as_str(), str::trim_start).starts_with(['-', '+', '(']) => None,
+        Some(inner) => parse_plain(&inner).map(|(n, _)| -n),
         None => parse_plain(t).map(|(n, _)| n),
     }
 }
@@ -593,11 +595,21 @@ mod tests {
 
     #[test]
     fn numbers_stored_as_text() {
-        for (text, n) in [("123", 123.0), (" 42 ", 42.0), ("-1,000.5", -1000.5), ("$3", 3.0), ("50%", 0.5), ("1E3", 1000.0), ("(100)", -100.0)] {
+        for (text, n) in [
+            ("123", 123.0),
+            (" 42 ", 42.0),
+            ("-1,000.5", -1000.5),
+            ("$3", 3.0),
+            ("50%", 0.5),
+            ("1E3", 1000.0),
+            ("(100)", -100.0),
+            ("$(5)", -5.0),
+            ("(5)%", -0.05),
+        ] {
             assert_eq!(number_stored_as_text(text), Some(n), "{text}");
         }
         // Dates, times, fractions, words and blanks are not flagged.
-        for text in ["3/4/2026", "10:30", "1 1/2", "abc", "12abc", "", "  ", "TRUE", "#N/A", "((1))"] {
+        for text in ["3/4/2026", "10:30", "1 1/2", "abc", "12abc", "", "  ", "TRUE", "#N/A", "((1))", "(-5)", "$(5)%", "(1/2)"] {
             assert_eq!(number_stored_as_text(text), None, "{text}");
         }
     }

crates/functions/src/financial.rs

@@ -30,7 +30,8 @@ fn pmt_calc(rate: f64, nper: f64, pv: f64, fv: f64, typ: f64) -> f64 {
     let k = 1.0 + rate * typ;
     if m > 0.0 {
         // (fv + pv*p) / (p - 1) = pv + (pv + fv) / (p - 1), without the cancellation in p - 1.
-        -(pv + (pv + fv) / m) * rate / k
+        // rate / m (about 1 / nper for a tiny rate) is taken first so (pv + fv) / m can't overflow.
+        -(pv * rate + (pv + fv) * (rate / m)) / k
     } else if m > -0.5 {
         // p near 1 from below: fv + pv*p = (pv + fv) + pv*m keeps the small terms that rounding p would drop.
         -(rate * (pv + fv + pv * m)) / (k * m)
@@ -1837,6 +1838,7 @@ mod tests {
         assert_eq!(ev("PMT", vec![n(5.0), n(1000.0), n(100.0)]), Value::Number(-500.0));
         assert_eq!(ev("PMT", vec![n(1e-300), n(10.0), n(100.0)]), Value::Number(-10.0));
         close_tol(ev("PMT", vec![n(1e-12), n(10.0), n(100.0)]), -10.000000000055001, 1e-15);
+        close_tol(ev("PMT", vec![n(1e-300), n(10.0), n(1e12)]), -1e11, 1e-15);
         close_tol(ev("PMT", vec![n(-0.999), n(5.0), n(100.0)]), -9.990_000_000_000_092e-14, 1e-15);
         close_tol(ev("PMT", vec![n(0.05), n(-10.0), n(100.0)]), 7.950_457_496_545_667, 1e-15);
         close_tol(ev("PMT", vec![n(-1e-17), n(1.0), n(1e18), n(-1e18)]), 10.0, 1e-9);

crates/functions/src/lookup.rs

@@ -31,7 +31,7 @@ fn needle(args: &[Arg], i: usize) -> R<Value> {
 /// The same holds for `=100+1E-14` against 100, and in every XLOOKUP / XMATCH mode.
 fn lookup_order(a: &Value, b: &Value) -> Ordering {
     match (a, b) {
-        (Value::Number(x), Value::Number(y)) => x.partial_cmp(y).unwrap_or(Ordering::Equal),
+        (Value::Number(x), Value::Number(y)) => x.partial_cmp(y).unwrap_or_else(|| compare(a, b)),
         _ => compare(a, b),
     }
 }

xtask/src/keytips.rs

@@ -58,7 +58,7 @@ struct Entry {
 impl Entry {
     /// The probe key: a command and the params its keytip passes.
     fn probe_key(&self) -> String {
-        if self.params.is_empty() { self.target.clone() } else { format!("{} {}", self.target, self.params) }
+        if self.params.is_empty() || self.params == "{}" { self.target.clone() } else { format!("{} {}", self.target, self.params) }
     }
 }