be more careful acting on unary "-"

in order to parse "-0." correctly, use the copysing functionality of C99
rather than using a=-a to invert the sign.

git-svn-id: http://svn.cactuscode.org/flesh/trunk@5125 17b73243-c579-4c4c-a9d2-2d5706c11dac

1 files changed, 3 insertions, 1 deletions

diff --git a/src/piraha/Call.cc b/src/piraha/Call.cc
index f4bfefe7..1f6969e8 100644
--- a/src/piraha/Call.cc
+++ b/src/piraha/Call.cc
@@ -542,7 +542,9 @@ smart_ptr<Value> meval(smart_ptr<Group> gr) {
                 if(ret->type == PIR_INT) {
                     ret->idata = -ret->idata;
                 } else if(ret->type == PIR_REAL) {
-                    ret->ddata = -ret->ddata;
+                    ret->ddata = std::copysign(ret->ddata,
+                                               std::signbit(ret->ddata) ?
+                                               1. : -1.);
                 } else {
                     std::ostringstream msg;
                     msg << "Unknown operation: " << unop << ret->type << std::endl;