ObjectiveExpr: The objective function.

ConstraintExpr: The constraint expression or a list of constraint expressions. Does not need to be a list if there is only one constraint.

ConstraintVal: The value of the constraint expression. This must be zero if the value has already been subtracted from the constraint expression. For example: lagrange(x+y, x²+y², 1, {x,y}) or lagrange(x+y, x²+y²-1, 0, {x,y}). Does not need to be a list if there is only one constraint.

VarList: The list of variables in the functions. 

Return value:
A matrix where each row of the matrix is a solution. The last column of the matrix is ObjectiveExpr evaluated at the point specified by the preceding columns. 

Examples:
1. Find the maximum and minimum values of x+y subject to the constraint x²+y²=1:
   lagrange( x+y, x²+y², 1, {x,y})
    [[sqrt(2)/2,   sqrt(2)/2,  sqrt(2)]
     [-sqrt(2)/2, -sqrt(2)/2, -sqrt(2)]]

  Row 1: x =  sqrt(2)/2,   y =  sqrt(2)/2,  x+y =  sqrt(2)  Maximum
  Row 2: x = -sqrt(2)/2,   y = -sqrt(2)/2,  x+y = -sqrt(2)  Minimum