Part 3: delegate and zoom
Part 2: property list storage and retrieval
Part 3: display line
Part 2: buildExpression
Part 2: buildExpressions 2
Part 2: doesExpressionHaveVariable
Part 2: bug fixes
Part 2: descriptionOfExpression working for sin/cos
Part 2: solveExpression
Part 2: doubleByEvaluatingArrayWithVariables category created
Part 2: evaluateMathematicalExpressionWithVariables working
Part 2: evaluateMathematicalExpressionWithVariables working