From ec0964861f86f7e1cd74a37a40e7c3997ee9f512 Mon Sep 17 00:00:00 2001
From: Sam Tobin-Hochstadt <samth@indiana.edu>
Date: Wed, 20 May 2020 15:30:32 -0400
Subject: [PATCH] Check for 0.0 imaginary part in `exp`.

Follows Chez Scheme and Guile. Turns `(exp 10000.+0.0i)` into
`+inf.0+0.0i` instead of `+inf.0+nan.0i`, which is analagous to
the behavior for exact 0 in the complex part.

Fixes #3194.
---
 pkgs/racket-test-core/tests/racket/number.rktl | 8 ++++++++
 racket/src/racket/src/number.c                 | 7 +++++++
 2 files changed, 15 insertions(+)

diff --git a/pkgs/racket-test-core/tests/racket/number.rktl b/pkgs/racket-test-core/tests/racket/number.rktl
index 57a750d3a1..a46c21fb8b 100644
--- a/pkgs/racket-test-core/tests/racket/number.rktl
+++ b/pkgs/racket-test-core/tests/racket/number.rktl
@@ -2243,6 +2243,14 @@
 (test 1.0 exp -0.0)
 (test 272.0 round (* 100 (exp 1)))
 
+;; should not be NaN
+(test +inf.0+0.0i exp 10000000.0+0.0i)
+(test +inf.0-0.0i exp 10000000.0-0.0i)
+#reader "maybe-single.rkt"
+(when has-single-flonum?
+  (test +inf.f+0.0f0i exp +100000.0f0+0.0f0i)
+  (test +inf.f-0.0f0i exp +100000.0f0-0.0f0i))
+
 (test 0 log 1)
 (test 0.0 log 1.0)
 (test -inf.0 log 0.0)
diff --git a/racket/src/racket/src/number.c b/racket/src/racket/src/number.c
index 661ec35476..d5ed8577df 100644
--- a/racket/src/racket/src/number.c
+++ b/racket/src/racket/src/number.c
@@ -2798,6 +2798,13 @@ static Scheme_Object *complex_exp(Scheme_Object *c)
   Scheme_Object *cos_a, *sin_a;
 
   r = exp_prim(1, &r);
+
+  /* If i is 0.0, avoid computing the cos/sin, since that can end up
+     producing NaN. */
+  if (SCHEME_FLOATP(i) && (SCHEME_FLOAT_VAL(i) == 0.0)) {
+    return scheme_make_complex(r, i);
+  }
+
   cos_a = cos_prim(1, &i);
   sin_a = sin_prim(1, &i);