Fix to issue #1348: add in a supported list to forbid trig functions …

…in student input.

doc/en/Authoring/Inputs/index.md

@@ -106,6 +106,7 @@ If you wish to forbid commas, then escape it with a backslash.
 There are groups of common keywords which you can forbid simply as
 
 * `[[BASIC-ALGEBRA]]` common algebraic operations such as `simplify`, `factor`, `expand`, `solve`, etc.
+* `[[BASIC-TRIG]]` names of all the trig and hyperbolic trig functions and their inverses, e.g.  `sin`, `asin`, `sinh`, `asinh`, etc.
 * `[[BASIC-CALCULUS]]` common calculus operations such as `int`, `diff`, `taylor`, etc.
 * `[[BASIC-MATRIX]]` common matrix operations such as `transpose`, `invert`, `charpoly`, etc.
 

stack/cas/cassecurity.class.php

@@ -73,6 +73,13 @@ class stack_cas_security {
             'trigrat' => true, 'trigreduce' => true, 'trigsign' => true,
             'trigsimp' => true, 'truncate' => true, 'decimalplaces' => true, 'simplify' => true,
         ],
+        '[[basic-trig]]' => [
+            'sin' => true, 'cos' => true, 'tan' => true, 'sec' => true, 'csc' => true, 'cot' => true, 
+            'asin' => true, 'acos' => true, 'atan' => true, 'asec' => true, 'acsc' => true, 'acot' => true,
+            'atan2' => true,
+            'sinh' => true, 'cosh' => true, 'tanh' => true, 'sech' => true, 'csch' => true, 'coth' => true, 
+            'asinh' => true, 'acosh' => true, 'atanh' => true, 'asech' => true, 'acsch' => true, 'acoth' => true,
+        ],
         '[[basic-calculus]]' => [
             'defint' => true, 'diff' => true, 'int' => true, 'integrate' => true,
             'limit' => true, 'partial' => true, 'desolve' => true, 'express' => true, 'taylor' => true,

tests/ast_container_test.php

@@ -324,6 +324,7 @@ public function test_check_external_forbidden_words_literal(): void {
             ['[x,y,z]', 'b,\,,c', false],
             ['diff(x^2,x)', '[[BASIC-CALCULUS]]', false], // From lists.
             ['solve((x-6)^4,x)', '[[BASIC-ALGEBRA]]', false], // From lists.
+            ['sin(A-B)', '[[BASIC-TRIG]]', false], // From lists.
         ];
 
         foreach ($cases as $case) {