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-rw-r--r--complex.c22
1 files changed, 22 insertions, 0 deletions
diff --git a/complex.c b/complex.c
index e9bfc02f7a..2b452e23c0 100644
--- a/complex.c
+++ b/complex.c
@@ -540,6 +540,28 @@ f_complex_polar(VALUE klass, VALUE x, VALUE y)
f_mul(x, m_sin(y)));
}
+/* returns a Complex or Float of ang*PI-rotated abs */
+VALUE
+rb_dbl_complex_polar(double abs, double ang)
+{
+ double fi;
+ const double fr = modf(ang, &fi);
+ int pos = fr == +0.5;
+
+ if (pos || fr == -0.5) {
+ if ((modf(fi / 2.0, &fi) != fr) ^ pos) abs = -abs;
+ return rb_complex_new(RFLOAT_0, DBL2NUM(abs));
+ }
+ else if (fr == 0.0) {
+ if (modf(fi / 2.0, &fi) != 0.0) abs = -abs;
+ return DBL2NUM(abs);
+ }
+ else {
+ ang *= M_PI;
+ return rb_complex_new(DBL2NUM(abs * cos(ang)), DBL2NUM(abs * sin(ang)));
+ }
+}
+
/*
* call-seq:
* Complex.polar(abs[, arg]) -> complex