From 7cb15a71912e8ed5937b10567c36f571cc93b143 Mon Sep 17 00:00:00 2001
From: Alex Shinn <alexshinn@gmail.com>
Date: Sun, 5 Jun 2016 22:25:18 +0900
Subject: [PATCH] Handling exact zero imaginary parts in complex asin. Fixes
 issue #350.

---
 bignum.c             | 16 ++++++++++------
 tests/r7rs-tests.scm |  3 +++
 2 files changed, 13 insertions(+), 6 deletions(-)

diff --git a/bignum.c b/bignum.c
index fc7e3624..6478c5de 100644
--- a/bignum.c
+++ b/bignum.c
@@ -1023,17 +1023,21 @@ sexp sexp_complex_asin (sexp ctx, sexp z) {
   sexp_gc_preserve2(ctx, res, tmp);
   res = sexp_complex_mul(ctx, z, z);
   tmp = sexp_make_complex(ctx, SEXP_ONE, SEXP_ZERO);
-  res = sexp_complex_sub(ctx, tmp, res);
-  res = sexp_complex_sqrt(ctx, res);
+  res = sexp_sub(ctx, tmp, res);
+  res = sexp_sqrt(ctx, NULL, 1, res);
   /* tmp = iz */
   sexp_complex_real(tmp) = sexp_complex_imag(z);
   sexp_negate(sexp_complex_real(tmp));
   sexp_complex_imag(tmp) = sexp_complex_real(z);
-  res = sexp_complex_add(ctx, tmp, res);
-  tmp = sexp_complex_log(ctx, res);
+  res = sexp_add(ctx, tmp, res);
+  tmp = sexp_log(ctx, NULL, 1, res);
   /* res = -i*tmp */
-  res = sexp_complex_copy(ctx, tmp);
-  sexp_negate(sexp_complex_imag(res));
+  if (sexp_complexp(tmp)) {
+    res = sexp_complex_copy(ctx, tmp);
+    sexp_negate(sexp_complex_imag(res));
+  } else {
+    res = tmp;
+  }
   sexp_gc_release2(ctx);
   return res;
 }
diff --git a/tests/r7rs-tests.scm b/tests/r7rs-tests.scm
index 5752222d..1c93c278 100644
--- a/tests/r7rs-tests.scm
+++ b/tests/r7rs-tests.scm
@@ -848,6 +848,9 @@
 (test 0.0 (inexact (acos 1))) ;; may return exact number
 (test 3.14159265358979 (acos -1))
 
+(test 0.0 (asin 0+0.0i))
+(test 1.5707963267948966 (acos 0+0.0i))
+
 (test 0.0 (atan 0.0 1.0))
 (test -0.0 (atan -0.0 1.0))
 (test 0.785398163397448 (atan 1.0 1.0))