From 4aa5e0a4a3d005c25cbd12c843e464a791340c1a Mon Sep 17 00:00:00 2001
From: HarmoGlace <23212967+HarmoGlace@users.noreply.github.com>
Date: Tue, 4 Apr 2023 14:33:26 +0200
Subject: [PATCH] Make behavior of calculation functions consistent (#515)

---
 library/src/compute/calc.rs | 45 +++++++++++++++++++++++++++++--------
 tests/typ/compute/calc.typ  | 20 +++++++++++++++++
 2 files changed, 56 insertions(+), 9 deletions(-)

diff --git a/library/src/compute/calc.rs b/library/src/compute/calc.rs
index ccc6e7b1d..c48c6816f 100644
--- a/library/src/compute/calc.rs
+++ b/library/src/compute/calc.rs
@@ -104,11 +104,23 @@ pub fn pow(
         _ => {}
     };
 
-    match (base, exp) {
+    let return_value = match (base, exp) {
         (Num::Int(a), Num::Int(b)) if b >= 0 => Value::Int(a.pow(b as u32)),
         (a, Num::Int(b)) => Value::Float(a.float().powi(b as i32)),
         (a, b) => Value::Float(a.float().powf(b.float())),
+    };
+
+    let is_nan = match return_value {
+        Value::Float(f) => f.is_nan(),
+        Value::Int(i) => (i as f64).is_nan(),
+        _ => false,
+    };
+
+    if is_nan {
+        bail!(span, "the return value is not a real number")
     }
+
+    return_value
 }
 
 /// Calculate the square root of a number.
@@ -367,20 +379,35 @@ pub fn tanh(
 /// Returns: float
 #[func]
 pub fn log(
-    /// The number whose logarithm to calculate.
-    value: f64,
-    /// The base of the logarithm.
+    /// The number whose logarithm to calculate. It must be strictly positive.
+    value: Spanned<Num>,
+    /// The base of the logarithm. It can't be null.
     #[named]
     #[default(10.0)]
     base: f64,
 ) -> Value {
-    Value::Float(if base == 2.0 {
-        value.log2()
+    let number = value.v.float();
+
+    if number <= 0 as f64 {
+        bail!(value.span, "a logarithm parameter must be strictly positive")
+    }
+    if !base.is_normal() {
+        bail!(value.span, "a logarithm base should be normal (not NaN, not infinite, non-null, not subnormal)")
+    }
+
+    let return_value = if base == 2.0 {
+        number.log2()
     } else if base == 10.0 {
-        value.log10()
+        number.log10()
     } else {
-        value.log(base)
-    })
+        number.log(base)
+    };
+
+    if return_value.is_infinite() || return_value.is_nan() {
+        bail!(value.span, "this logarithm doesn't return a real value")
+    }
+
+    Value::Float(return_value)
 }
 
 /// Round a number down to the nearest integer.
diff --git a/tests/typ/compute/calc.typ b/tests/typ/compute/calc.typ
index 51569f7ae..b7c6df02f 100644
--- a/tests/typ/compute/calc.typ
+++ b/tests/typ/compute/calc.typ
@@ -93,6 +93,26 @@
 // Error: 14-36 exponent may not be NaN, infinite, or subnormal
 #calc.pow(2, calc.pow(2.0, 10000.0))
 
+---
+// Error: 15-18 the return value is not a real number
+#calc.pow(-1, 0.5)
+
+---
+// Error: 12-14 cannot take square root of negative number
+#calc.sqrt(-1)
+
+---
+// Error: 11-13 a logarithm parameter must be strictly positive
+#calc.log(-1)
+
+---
+// Error: 11-12 a logarithm base should be normal (not NaN, not infinite, non-null, not subnormal)
+#calc.log(1, base: 0)
+
+---
+// Error: 11-13 this logarithm doesn't return a real value
+#calc.log(10, base: -1)
+
 ---
 // Error: 10-12 expected at least one value
 #calc.min()