From b712756e74e3e3c101064bbefc1d062b73d11443 Mon Sep 17 00:00:00 2001
From: Arun Isaac
Date: Tue, 23 Feb 2021 16:29:44 +0530
Subject: Implement the lower incomplete gamma function as a scheme wrapper.

With this change, the wrapper around the gsl lower incomplete gamma
function is directly in scheme. Earlier, there was one layer of
wrapping in C which needed to be wrapped again in scheme.

* include/utils.h (lower_incomplete_gamma): Delete function.
* src/utils.sc (lower-incomplete-gamma): Delete function.
* scm/extent-sampling/wrap.scm (lower-incomplete-gamma): New function.
---
 scm/extent-sampling/wrap.scm | 10 ++++++++++
 1 file changed, 10 insertions(+)

(limited to 'scm/extent-sampling')

diff --git a/scm/extent-sampling/wrap.scm b/scm/extent-sampling/wrap.scm
index 65fd7ad..0e32452 100644
--- a/scm/extent-sampling/wrap.scm
+++ b/scm/extent-sampling/wrap.scm
@@ -30,6 +30,16 @@
                       (dynamic-func "surface_area_of_ball" lib-extentsampling)
                       (list int)))
 
+(define-public (lower-incomplete-gamma s x)
+  (* ((pointer->procedure double
+                          (dynamic-func "gsl_sf_gamma" lib-gsl)
+                          (list double))
+      s)
+     ((pointer->procedure double
+                          (dynamic-func "gsl_sf_gamma_inc_P" lib-gsl)
+                          (list double double))
+      s x)))
+
 (define-public angle-between-vectors
   (pointer->procedure double
                       (dynamic-func "angle_between_vectors" lib-extentsampling)
-- 
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