From f089b2001f57454541a8ba37da649b27ae3b69ea Mon Sep 17 00:00:00 2001
From: Calvin Rose <calsrose@gmail.com>
Date: Sat, 4 Apr 2020 12:51:47 -0500
Subject: [PATCH] Add several math functions to the math module.

---
 CHANGELOG.md    |  4 ++++
 src/core/math.c | 30 ++++++++++++++++++++++++++++++
 2 files changed, 34 insertions(+)

diff --git a/CHANGELOG.md b/CHANGELOG.md
index b1ae5089..804ea624 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -2,6 +2,10 @@
 All notable changes to this project will be documented in this file.
 
 ## Unreleased - ???
+- Add `math/erf`
+- Add `math/erfc`
+- Add `math/log1p`
+- Add `math/next`
 - Add os/umask
 - Add os/perm-int
 - Add os/perm-string
diff --git a/src/core/math.c b/src/core/math.c
index 5d853d07..b1c3fda9 100644
--- a/src/core/math.c
+++ b/src/core/math.c
@@ -255,6 +255,10 @@ JANET_DEFINE_MATHOP(fabs, fabs)
 JANET_DEFINE_MATHOP(floor, floor)
 JANET_DEFINE_MATHOP(trunc, trunc)
 JANET_DEFINE_MATHOP(round, round)
+JANET_DEFINE_MATHOP(gamma, lgamma)
+JANET_DEFINE_MATHOP(log1p, log1p)
+JANET_DEFINE_MATHOP(erf, erf)
+JANET_DEFINE_MATHOP(erfc, erfc)
 
 #define JANET_DEFINE_MATH2OP(name, fop)\
 static Janet janet_##name(int32_t argc, Janet *argv) {\
@@ -267,6 +271,7 @@ static Janet janet_##name(int32_t argc, Janet *argv) {\
 JANET_DEFINE_MATH2OP(atan2, atan2)
 JANET_DEFINE_MATH2OP(pow, pow)
 JANET_DEFINE_MATH2OP(hypot, hypot)
+JANET_DEFINE_MATH2OP(nextafter, nextafter)
 
 static Janet janet_not(int32_t argc, Janet *argv) {
     janet_fixarity(argc, 1);
@@ -438,6 +443,26 @@ static const JanetReg math_cfuns[] = {
         JDOC("(math/exp2 x)\n\n"
              "Returns 2 to the power of x.")
     },
+    {
+        "math/log1p", janet_log1p,
+        JDOC("(math/log1p x)\n\n"
+             "Returns (log base e of x) + 1 more accurately than (+ (math/log x) 1)")
+    },
+    {
+        "math/gamma", janet_gamma,
+        JDOC("(math/gamma x)\n\n"
+             "Returns gamma(x).")
+    },
+    {
+        "math/erfc", janet_erfc,
+        JDOC("(math/erfc x)\n\n"
+             "Returns the complementary error function of x.")
+    },
+    {
+        "math/erf", janet_erf,
+        JDOC("(math/erf x)\n\n"
+             "Returns the error function of x.")
+    },
     {
         "math/expm1", janet_expm1,
         JDOC("(math/expm1 x)\n\n"
@@ -453,6 +478,11 @@ static const JanetReg math_cfuns[] = {
         JDOC("(math/round x)\n\n"
              "Returns the integer nearest to x.")
     },
+    {
+        "math/next", janet_nextafter,
+        JDOC("(math/next y)\n\n"
+             "Returns the next representable floating point value after x in the direction of y.")
+    },
     {NULL, NULL, NULL}
 };