loncom/homework/response.pm - diff

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-version 1.155, 2006/12/15 21:10:13
+version 1.156, 2006/12/15 22:11:43
  Line 535  sub end_mathresponse {
      return $result;
  }
+ sub implicit_multiplication {
+     my ($expression)=@_;
+ # Escape scientific notation, so 3e8 does not become 3*e*8
+ # 3e8 -> 3&8; 3e-8 -> 3&-8; 3E+8 -> e&+8
+     $expression=~s/(\d+)e([\+\-]*\d+)/$1\&\($2\)/gsi;
+ # 3x10^8 -> 3&8; 3*10^-8 -> 3&-8
+     $expression=~s/(\d+)(?:x|\*)10(?:\^|\*\*)([\+\-]*\d+)/$1\&\($2\)/gsi;
+ # Fill in multiplication signs
+ # a b -> a*b;3 b -> 3*b;3 4 -> 3*4
+     $expression=~s/(\w)\s+(\w)/$1\*$2/gs;
+ # )( -> )*(; ) ( -> )*(
+     $expression=~s/\)\s*\(/\)\*\(/gs;
+ # 3a -> 3*a; 3( -> 3*(; 3 ( -> 3*(; 3A -> 3*A
+     $expression=~s/(\d)\s*([a-zA-Z\(])/$1\*$2/gs;
+ # a ( -> a*(
+     $expression=~s/(\w)\s+\(/$1\*\(/gs;
+ # )a -> )*a; )3 -> )*3; ) 3 -> )*3
+     $expression=~s/\)\s*(\w)/\)\*$1/gs;
+ # 3&8 -> 3e8; 3&-4 -> 3e-4
+     $expression=~s/(\d+)\&\(([\+\-]*\d+)\)/$1e$2/gs;
+     return $expression;
+ }
  sub start_answer {
      my ($target,$token,$tagstack,$parstack,$parser,$safeeval)=@_;