more complete set of math functions

1 files changed, 41 insertions, 11 deletions

diff --git a/parser.php b/parser.php
index b5bbaba..fd58f4c 100644
--- a/parser.php
+++ b/parser.php
@@ -1139,6 +1139,18 @@ class qtype_algebra_parser_special extends qtype_algebra_parser_term {
     );
 }
 
+/**
+ * implement math functions that aren't php builtins
+ */
+function log2($arg)
+{
+    return log($arg, 2);
+}
+
+function ln($arg)
+{
+    return log($arg);
+}
 
 /**
  * Class representing a function in an algebraic expression.
@@ -1158,6 +1170,9 @@ class qtype_algebra_parser_function extends qtype_algebra_parser_term {
      * @param $text string matching the function's regular expression
      */
     public function __construct($text) {
+        if ($text == 'log') {
+            throw new parser_exception(get_string('deprecatedlog', 'qtype_algebra'));
+        }
         if (!function_exists($text) and !array_key_exists($text, self::$fnmap)) {
             throw new parser_exception(get_string('undefinedfunction', 'qtype_algebra', $text));
         }
@@ -1284,14 +1299,21 @@ class qtype_algebra_parser_function extends qtype_algebra_parser_term {
 
     // Static class properties.
     const NARGS = 1;
-    public static $fnmap = array ('ln' => 'log',
-                                  'log' => 'log10'
-                                  );
-    public static $texmap = array('asin' => '\\sin^{-1}',
-                                  'acos' => '\\cos^{-1}',
-                                  'atan' => '\\tan^{-1}',
-                                  'sqrt' => '\\sqrt'
+     /* fnmap is not needed, since all needed
+      *   functions are implemented without pseudonyms
+      */
+    public static $fnmap = array ();
+    public static $texmap = array('sqrt'  => '\\sqrt',
+                                  'log2'  => '\\log_{2}',
+                                  'log10' => '\\log_{10}',
+                                  'asin'  => '\\sin^{-1}',
+                                  'acos'  => '\\cos^{-1}',
+                                  'atan'  => '\\tan^{-1}',
+                                  'asinh' => '\\sinh^{-1}',
+                                  'acosh' => '\\cosh^{-1}',
+                                  'atanh' => '\\tanh^{-1}',
                                   );
+
     // List of functions requiring special brackets.
     public static $bracketmap = array ('sqrt'
                                        );
@@ -1404,18 +1426,26 @@ class qtype_algebra_parser {
         'e'
     );
 
-    // Functions which the parser will understand. These should all be standard PHP math functions.
+    // Functions which the parser will understand.
+    // You have to implement any that are not standard PHP math functions.
     public static $functions = array ('sqrt',
+                                      'exp',
+                                      'log2',
                                       'ln',
                                       'log',
-                                      'cosh',
+                                      'log10',
                                       'sinh',
+                                      'cosh',
+                                      'tanh',
                                       'sin',
                                       'cos',
                                       'tan',
                                       'asin',
                                       'acos',
-                                      'atan'
+                                      'atan',
+                                      'asinh',
+                                      'acosh',
+                                      'atanh',
                                       );
 
     // Array to define the priority of the different operations. The parser implements the standard BODMAS priority:
@@ -1461,7 +1491,7 @@ class qtype_algebra_parser {
     }
 
     /**
-     * Parses a given string containing an algebric epxression and returns the corresponding parse tree.
+     * Parses a given string containing an algebric expression and returns the corresponding parse tree.
      *
      * This method loops over the string using the regular expressions in the token map to break down the
      * string into tokens. These tokens are arranged into a structured stack, taking account of the