[Aimmath-commit] AIM/WEB-INF/maple/aim AnswerHints.mpl,NONE,1.1

[<mo...@us...>]

Update of /cvsroot/aimmath/AIM/WEB-INF/maple/aim
In directory sc8-pr-cvs1:/tmp/cvs-serv13337

Added Files:
	AnswerHints.mpl 
Log Message:
Starting a new package: AnswerHints. Similar to SyntaxHints, but for catching mathematical errors, not syntax errors.

--- NEW FILE: AnswerHints.mpl ---

# Copyright (C) 2003 Ken Monks
# Distributed without warranty under the GPL - see README for details

read("Package.mpl"):
Package("aim/AnswerHints",
"This package contains functions that check for common mathematical errors 
 (as opposed to syntax errors) in a student's answer and provide some 
 guidance to them about possible causes for errors in their answers.
"):

######################################################################

`Package/Assign`(
 `Hints/CheckSigns`::boolean,
 "This routine returns @true@ if it can determine if @ans@ differs
  from the @rightans@ only by having the wrong signs in zero or more
  subexpressions. Note that this routine will also return @true@ if @ans@
  is equal to @rightans@. 
 ",
 proc(ans,rightans)
  local And,elt,relt,absans,absrightans,Member;

  if type(rightans,InertExpr) then 
    return `Hints/CheckSigns`(ans,Value(rightans))
  elif type(rightans,SET) then
    return `Hints/CheckSigns`(ans,rightans['toSet'])
  fi:

  And:=proc() evalb({args}={true}); end:
  Member:=proc(e,S)
     local i:
     for i in S do
      if `Hints/CheckSigns`(e,i) then return i fi:
     od:
     return NULL:
  end:

  try
    if type({ans,rightans},{set(list)}) then
      return nops(ans)=nops(rightans) and
         And(op(zip(`Hints/CheckSigns`,ans,rightans)))
    elif type({ans,rightans},{set(set)}) then
      if nops(ans)<>nops(rightans) then return false fi:
      absans:=map(abs,ans); absrightans:=map(abs,rightans);
      for elt in absans do
        relt:=Member(elt,absrightans);
        if relt=NULL then 
          return false 
        else
          absrightans:=absrightans minus {relt}; 
        fi:
      od:
      return true;
    elif type({ans,rightans},set(function)) or
         type({ans,rightans},set(`^`)) then
      return op(0,ans)=op(0,rightans) and  
        nops(ans)=nops(rightans) and
       `Hints/CheckSigns`([op(ans)],[op(rightans)]);
    elif type({ans,rightans},set(`+`)) or
         type({ans,rightans},set(`*`)) then
      return `Hints/CheckSigns`({op(ans)},{op(rightans)})        
    elif type({ans,rightans},set(algebraic)) then
      return `aim/Test`(abs(ans),abs(rightans)) 
     fi:
  catch : end:
  return false;  
 end
):

EndPackage():