[goffice] Complex: improve div

[Morten Welinder <mortenw src gnome org>]

commit a978bf4603fa3499985c0b1bdd1478fde94f3ae5
Author: Morten Welinder <terra gnome org>
Date:   Sat Feb 6 11:27:37 2016 -0500

    Complex: improve div

 ChangeLog                 |    6 ++++++
 NEWS                      |    1 +
 goffice/math/go-complex.c |    6 +++---
 goffice/math/go-complex.h |    2 ++
 4 files changed, 12 insertions(+), 3 deletions(-)
---
diff --git a/ChangeLog b/ChangeLog
index 9a175d0..d3d2116 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,7 +1,13 @@
+2016-02-06  Morten Welinder  <terra gnome org>
+
+       * goffice/math/go-complex.c (go_complex_from_polar_pi): Make this
+       public.
+
 2016-02-02  Morten Welinder  <terra gnome org>
 
        * goffice/math/go-complex.c (go_complex_powl): Fix real case
        accuracy.
+       (go_complex_div): Avoid intermediate underflow when possible.
 
 2016-01-29  Jean Brefort  <jean brefort normalesup org>
 
diff --git a/NEWS b/NEWS
index 71dc8d7..6e65e0c 100644
--- a/NEWS
+++ b/NEWS
@@ -7,6 +7,7 @@ Jean:
        * Add title to axis lines. [#760675]
 Morten:
        * Fix go_complex_powl accuracy for real case.
+       * Fix go_complex_div for very small divisor.
 
 --------------------------------------------------------------------------
 goffice 0.10.26:
diff --git a/goffice/math/go-complex.c b/goffice/math/go-complex.c
index f1765be..abab90e 100644
--- a/goffice/math/go-complex.c
+++ b/goffice/math/go-complex.c
@@ -195,7 +195,7 @@ SUFFIX(go_complex_from_polar) (COMPLEX *dst, DOUBLE mod, DOUBLE angle)
                                 mod * SUFFIX(sin) (angle));
 }
 
-static  void
+void
 SUFFIX(go_complex_from_polar_pi) (COMPLEX *dst, DOUBLE mod, DOUBLE angle)
 {
        SUFFIX(go_complex_init) (dst,
@@ -220,8 +220,8 @@ SUFFIX(go_complex_div) (COMPLEX *dst, COMPLEX const *a, COMPLEX const *b)
 {
        DOUBLE bmod = SUFFIX(go_complex_mod) (b);
 
-       if (bmod >= GO_const(1e10)) {
-               /* Ok, it's big.  */
+       if (bmod >= GO_const(1e10) || bmod < GO_const(1e-10)) {
+               /* Ok, it's very big or very small.  */
                DOUBLE a_re = a->re / bmod;
                DOUBLE a_im = a->im / bmod;
                DOUBLE b_re = b->re / bmod;
diff --git a/goffice/math/go-complex.h b/goffice/math/go-complex.h
index 7620c64..9746883 100644
--- a/goffice/math/go-complex.h
+++ b/goffice/math/go-complex.h
@@ -28,6 +28,7 @@ int go_complex_from_string (GOComplex *dst, char const *src, char *imunit);
 
 void go_complex_to_polar (double *mod, double *angle, GOComplex const *src);
 void go_complex_from_polar (GOComplex *dst, double mod, double angle);
+void go_complex_from_polar_pi (GOComplex *dst, double mod, double angle);
 void go_complex_mul  (GOComplex *dst, GOComplex const *a, GOComplex const *b);
 void go_complex_div  (GOComplex *dst, GOComplex const *a, GOComplex const *b);
 void go_complex_pow  (GOComplex *dst, GOComplex const *a, GOComplex const *b);
@@ -63,6 +64,7 @@ int go_complex_from_stringl (GOComplexl *dst, char const *src, char *imunit);
 
 void go_complex_to_polarl (long double *mod, long double *angle, GOComplexl const *src);
 void go_complex_from_polarl (GOComplexl *dst, long double mod, long double angle);
+void go_complex_from_polar_pil (GOComplexl *dst, long double mod, long double angle);
 void go_complex_mull  (GOComplexl *dst, GOComplexl const *a, GOComplexl const *b);
 void go_complex_divl  (GOComplexl *dst, GOComplexl const *a, GOComplexl const *b);
 void go_complex_powl  (GOComplexl *dst, GOComplexl const *a, GOComplexl const *b);