From 0a21f890aeafebc15c4b064707a7ace229262dc2 Mon Sep 17 00:00:00 2001
From: Pekka Laiho <pekka.i.laiho@gmail.com>
Date: Mon, 8 Jun 2020 10:14:32 +0700
Subject: [PATCH] add more math functions

---
 src/Lib/Math.php | 56 ++++++++++++++++++++++++++++++++++++++++++++----
 1 file changed, 52 insertions(+), 4 deletions(-)

diff --git a/src/Lib/Math.php b/src/Lib/Math.php
index a8ddba0..72d9f50 100644
--- a/src/Lib/Math.php
+++ b/src/Lib/Math.php
@@ -10,15 +10,19 @@ class Math implements ILib
     {
         // Basic arithmetic
 
-        $env->set('+', new CoreFunc('+', 'Return the sum of all arguments.', 2, -1,
+        $env->set('+', new CoreFunc('+', 'Return the sum of all arguments.', 1, -1,
             function (...$args) {
                 return array_sum($args);
             }
         ));
 
-        $env->set('-', new CoreFunc('-', 'Subtract the other arguments from the first.', 2, -1,
+        $env->set('-', new CoreFunc('-', 'Subtract the other arguments from the first.', 1, -1,
             function (...$args) {
-                return array_reduce(array_slice($args, 1), fn ($a, $b) => $a - $b, $args[0]);
+                if (count($args) == 1) {
+                    return -$args[0];
+                } else {
+                    return array_reduce(array_slice($args, 1), fn ($a, $b) => $a - $b, $args[0]);
+                }
             }
         ));
 
@@ -46,6 +50,50 @@ class Math implements ILib
             }
         ));
 
-        // TODO: add pow, sqrt, floor, ceil, abs
+        // Helpers for change by 1
+
+        $env->set('inc', new CoreFunc('inc', 'Increase argument by one.', 1, 1,
+            fn ($a) => $a + 1
+        ));
+
+        $env->set('dec', new CoreFunc('dec', 'Decrease argument by one.', 1, 1,
+            fn ($a) => $a - 1
+        ));
+
+        // Trigonometry
+
+        $env->set('sin', new CoreFunc('sin', 'Calculate the sine of argument.', 1, 1,
+            fn ($a) => sin($a)
+        ));
+
+        $env->set('cos', new CoreFunc('cos', 'Calculate the cosine of argument.', 1, 1,
+            fn ($a) => cos($a)
+        ));
+
+        $env->set('tan', new CoreFunc('tan', 'Calculate the tangent of argument.', 1, 1,
+            fn ($a) => tan($a)
+        ));
+
+        // Other
+
+        $env->set('abs', new CoreFunc('abs', 'Return the absolute value of argument.', 1, 1,
+            fn ($a) => abs($a)
+        ));
+
+        $env->set('floor', new CoreFunc('floor', 'Return the next lowest integer by rounding argument down.', 1, 1,
+            fn ($a) => intval(floor($a))
+        ));
+
+        $env->set('ceil', new CoreFunc('ceil', 'Return the next highest integer by rounding argument up.', 1, 1,
+            fn ($a) => intval(ceil($a))
+        ));
+
+        $env->set('pow', new CoreFunc('pow', 'Return the first argument raised to the power of second argument.', 2, 2,
+            fn ($a, $b) => pow($a, $b)
+        ));
+
+        $env->set('sqrt', new CoreFunc('sqrt', 'Return the square root of the arguemnt.', 1, 1,
+            fn ($a) => sqrt($a)
+        ));
     }
 }