[goffice] GOQuad: add log function.

[Morten Welinder <mortenw src gnome org>]

commit 63a34f2f6f88647dfa5a4212f4fb1e2121533a65
Author: Morten Welinder <terra gnome org>
Date:   Thu Dec 5 11:09:49 2013 -0500

    GOQuad: add log function.

 ChangeLog              |    7 +++++++
 NEWS                   |    1 +
 goffice/math/go-quad.c |   40 +++++++++++++++++++++++++++++++++++++++-
 goffice/math/go-quad.h |    4 ++++
 tests/test-quad.c      |    1 +
 5 files changed, 52 insertions(+), 1 deletions(-)
---
diff --git a/ChangeLog b/ChangeLog
index 6a329f4..c5abb55 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,10 @@
+2013-12-05  Morten Welinder  <terra gnome org>
+
+       * goffice/math/go-quad.c (go_quad_pi): New constant.
+       (go_quad_log): New function.
+
+       * tests/test-quad.c (main): Check value of go_quad_2pi.
+
 2013-12-04  Morten Welinder  <terra gnome org>
 
        * goffice/math/go-complex.c (go_complex_pow): Fix class over
diff --git a/NEWS b/NEWS
index 0f1107f..be39466 100644
--- a/NEWS
+++ b/NEWS
@@ -5,6 +5,7 @@ Jean
 
 Morten:
        * Improve complex math.
+       * Add quad precision log function.
 
 --------------------------------------------------------------------------
 goffice 0.10.9:
diff --git a/goffice/math/go-quad.c b/goffice/math/go-quad.c
index d16bd6f..87fda74 100644
--- a/goffice/math/go-quad.c
+++ b/goffice/math/go-quad.c
@@ -215,6 +215,12 @@ SUFFIX(go_quad_start) (void)
                                           256.0,
                                           256.0);
 
+               SUFFIX(go_quad_constant8) ((QUAD *)&SUFFIX(go_quad_2pi),
+                                          pi_hex_digits,
+                                          G_N_ELEMENTS (pi_hex_digits),
+                                          256.0,
+                                          512.0);
+
                SUFFIX(go_quad_constant8) ((QUAD *)&SUFFIX(go_quad_e),
                                           e_hex_digits,
                                           G_N_ELEMENTS (e_hex_digits),
@@ -265,9 +271,10 @@ SUFFIX(go_quad_end) (void *state)
        g_free (state);
 }
 
-const QUAD SUFFIX(go_quad_zero);
+const QUAD SUFFIX(go_quad_zero) = { 0, 0 };
 const QUAD SUFFIX(go_quad_one) = { 1, 0 };
 const QUAD SUFFIX(go_quad_pi);
+const QUAD SUFFIX(go_quad_2pi);
 const QUAD SUFFIX(go_quad_e);
 const QUAD SUFFIX(go_quad_ln2);
 const QUAD SUFFIX(go_quad_sqrt2);
@@ -734,3 +741,34 @@ SUFFIX(go_quad_expm1) (QUAD *res, const QUAD *a)
                SUFFIX(go_quad_div) (res, &z, &zp1);
        }
 }
+
+/**
+ * go_quad_log: (skip)
+ **/
+/**
+ * go_quad_logl: (skip)
+ **/
+void
+SUFFIX(go_quad_log) (QUAD *res, const QUAD *a)
+{
+       DOUBLE da = SUFFIX(go_quad_value) (a);
+
+       if (da == 0)
+               SUFFIX(go_quad_init) (res, SUFFIX(go_ninf));
+       else if (da < 0)
+               SUFFIX(go_quad_init) (res, SUFFIX(go_nan));
+       else if (!SUFFIX(go_finite) (da))
+               *res = *a;
+       else {
+               QUAD xi, yi, dx;
+               SUFFIX(go_quad_init) (&xi, SUFFIX(log) (da));
+
+               /* Newton step. */
+               SUFFIX(go_quad_exp) (&yi, NULL, &xi);
+               SUFFIX(go_quad_sub) (&dx, a, &yi);
+               SUFFIX(go_quad_div) (&dx, &dx, &yi);
+               SUFFIX(go_quad_add) (&xi, &xi, &dx);
+               
+               *res = xi;
+       }
+}
diff --git a/goffice/math/go-quad.h b/goffice/math/go-quad.h
index 1ffe022..76f40a0 100644
--- a/goffice/math/go-quad.h
+++ b/goffice/math/go-quad.h
@@ -26,6 +26,7 @@ void go_quad_floor (GOQuad *res, const GOQuad *a);
 void go_quad_pow (GOQuad *res, double *exp2, const GOQuad *x, const GOQuad *y);
 void go_quad_exp (GOQuad *res, double *exp2, const GOQuad *a);
 void go_quad_expm1 (GOQuad *res, const GOQuad *a);
+void go_quad_log (GOQuad *res, const GOQuad *a);
 
 void go_quad_mul12 (GOQuad *res, double x, double y);
 
@@ -36,6 +37,7 @@ void go_quad_constant8 (GOQuad *res, const guint8 *data, gsize n, double base, d
 GO_VAR_DECL const GOQuad go_quad_zero;
 GO_VAR_DECL const GOQuad go_quad_one;
 GO_VAR_DECL const GOQuad go_quad_pi;
+GO_VAR_DECL const GOQuad go_quad_2pi;
 GO_VAR_DECL const GOQuad go_quad_e;
 GO_VAR_DECL const GOQuad go_quad_ln2;
 GO_VAR_DECL const GOQuad go_quad_sqrt2;
@@ -63,6 +65,7 @@ void go_quad_floorl (GOQuadl *res, const GOQuadl *a);
 void go_quad_powl (GOQuadl *res, long double *exp2, const GOQuadl *x, const GOQuadl *y);
 void go_quad_expl (GOQuadl *res, long double *exp2, const GOQuadl *a);
 void go_quad_expm1l (GOQuadl *res, const GOQuadl *a);
+void go_quad_logl (GOQuadl *res, const GOQuadl *a);
 
 void go_quad_mul12l (GOQuadl *res, long double x, long double y);
 
@@ -74,6 +77,7 @@ void go_quad_constant8l (GOQuadl *res, const guint8 *data, gsize n, long double
 GO_VAR_DECL const GOQuadl go_quad_zerol;
 GO_VAR_DECL const GOQuadl go_quad_onel;
 GO_VAR_DECL const GOQuadl go_quad_pil;
+GO_VAR_DECL const GOQuadl go_quad_2pil;
 GO_VAR_DECL const GOQuadl go_quad_el;
 GO_VAR_DECL const GOQuadl go_quad_ln2l;
 GO_VAR_DECL const GOQuadl go_quad_sqrt2l;
diff --git a/tests/test-quad.c b/tests/test-quad.c
index a8a3a80..7ae5991 100644
--- a/tests/test-quad.c
+++ b/tests/test-quad.c
@@ -224,6 +224,7 @@ main (int argc, char **argv)
        g_assert (go_quad_value (&c) == ldexp (1.0, -80));
 
        g_assert (fabs (go_quad_value (&go_quad_pi) - M_PI) < 1e-14);
+       g_assert (fabs (go_quad_value (&go_quad_2pi) - 2 * M_PI) < 1e-14);
        g_assert (fabs (go_quad_value (&go_quad_e) - exp(1)) < 1e-14);
        g_assert (fabs (go_quad_value (&go_quad_ln2) - log(2)) < 1e-14);
        g_assert (go_quad_value (&go_quad_zero) == 0);