Get a function of one variable whose value at a real number x is computed by assigning x to the variable v and then returning the value of the expression associated with this ExpressionInput. Of couse, v should be one of the variables registered with the Parser for this ExpressionInput, or else in can never occur in the expression. Note that the value of the variable v changes TEMPORARILY when the function is evaluated. (So you should not use a variable where setting the value has a side effect, such as the variable associated with a SliderVariable.)
Referenced by EpsilonDelta::setUpCanvas().