Problem Techniques
Any additions to the indexed snippets below should use the same format. A suggested model is provided in this snippet template.
Contents
Index of Problem Coding Techniques
This index links to problem code snippets that quickly show how to accomplish each effect. Each has limited explanation that assumes a basic understanding of how PG files are written. If you want more details, please see the MathObjects documentation, POD documentation, PG macro files, and PG library files.
 MathObjects documentation Written by Davide Cervone
 POD documentation (POD  Plain Old Documentation)
 PG macro files Source code for pg/macros files.
 PG library files Source code for pg/lib files.
Topics AB
 Accuracy Required for Numerical Answers
 Adaptive Parameters in Answers
 Adding New Functions to the Context
 Adding Labels, Lines and Points to Dynamic Graphs
 Algebraic Fractions in Student Answers
 Aligned Answer Blanks
 Allowing Strings (Text) in Student Answers
 Answer Blank in the Exponent
 Answer Format Help
 Answer Hints
 Answer is a Solution to an Equation
 Any Answer Marked Correct
 Antiderivatives and Indefinite Integrals
 Applet Example: Flash
 Applet Example: GeoGebra
 Applet Example: Embedding Sage
 Applet Example: Draggable Statements
 Arrows in Dynamic Graphs
 AskSage subroutine for using Sage
Topics CD
 Comments (for Instructors) Visible in the Problem Library
 Composition of Functions as Correct Answer
 Compound (Multipart, sequential) Problems (see also Scaffold)
 Constants in Problems
 Constant Differences (Additive) Between Student and Correct Answers
 Constant Differences Between Student and Correct Answers
 Custom Answer Checkers
 Custom Error Messages
 Draggable Statements
 Difference Quotients as Correct Answers
 Differentiating Formulas
 Digits TolType
 Disabling Functions and Operators in Student Answers
 Domain of Function Evaluation
Topics EF
 Equation Answer Evaluation (Implicit)
 Equations Defining Functions (Not Implicit)

eval()
Versussubstitute()
 Error Message Customization
 Extracting Coordinates of a Point
 Finding the norm of a Vector
 Factoring and Expanding Polynomials
 Flash Applets (Deprecated. Browsers have stopped supporting Flash.)
 Flash Applet Point and Graph Example (Deprecated. Browsers have stopped supporting Flash.)
 Formatting Correct Answers: Equations
 Formatting Correct Answers: Numbers and Formulas
 Formatting: Decimals
 Formatting Fractions as Student Answers
 Formula Answer Evaluation; Limits for Evaluation
 Formula Answer Evaluation; Test Points
 Formulas with Units, as Answers
 Formulas with Variables Other than x
 Fractions (Algebraic) as Student Answers
 Functions Added to the Context
 Function Answers Up To Additive Constants
 Function Composition as Correct Answer
Topics GH
 Graphic Images, Dynamically Generated
 Graphic Images, Dynamic, with Labels, Lines and Points
 Graphic Images, Dynamic, with Filled Regions
 Graphic Images, with Parametric Functions
 Graphic Images, Put Into Tables
 Graphic Images, Static
 Graphic Image, TikZ Images
 Graphing in 2D with Contour Plots
 Graphing in 2D with Contour Plots that Have a Color Gradient
 Graphing in 2D with Slope Fields
 Graphing in 2D with Vector Fields
 Graphing in 3D with Cylindrical Coordinates
 Graphing in 3D with Rectangular Coordinates
 Graphing in 3D with Parametric Curves
 Graphing in 3D with Parametric Surfaces (e.g., Spherical Coordinates)
 Graphing in 3D with Vector Fields
 Graph Tool, a way for students to input graphs as answers
 Hints in Problems
 HTML Links in Problems
Topics IJ
Topics KL
 Knowls
 Labels on Dynamically Generated Graphs
 Limits over which Formulas are Evaluated
 Lines in Dynamically Generated Graphs
 Linked Answer Blanks
 Linking Successive Problems
 Links to Other Web Pages
 Lists as Answers
 Logarithms
Topics MN
 Matching Problems
 Matching Problems That Have Static Graphic Images
 Matching Problems That Have Dynamic Graphic Images
 Month, Day or Year as a problem variable
 Multiple Choice Problems
 Multiple Choice Problems with Graphic Images (see example 1)
 Multiple Select Problems (Select All That Apply or Checkbox Multiple Choice)
 MultiAnswer, Self Referential Problems
 MultiPart, Sequential Problems
 Named Answer Rules
 Named (Numerical) Constants in Problems
 Numbers with Units, as Answers
 Numerical Answer Evaluation Tolerance
 Numerical Constants in Problems
 Numerical Tolerance in Problems
Topics OP
 Parameters (Adaptive) in Answers
 Parametric Equations as Answers
 Parametric Lines as Answers
 Periodic Answers
 Planes or Lines Defined Implicitly
 Plotting Parametric Equations
 Plotting Lines and Points on Dynamically Generated Graphs
 Points in Dynamically Generated Graphs
 Points in Student Answers
 Popup Lists
 Popup Lists For Many Questions With Common Answers
Topics QR
 Radio Buttons and Multiple Choice Problems
 Recursively Defined Functions
 Rerandomize Problem allow student to choose a different version. Also see Show Me Another.
 Restricting Allowed Functions in Student Answers
 Restricting Allowed Operators in Student Answers
 Restricting Student Answer Formats
Topics ST
 Scaffolded (or "sequential", or "compound") problems. Reveal parts consecutively.
 Slope Field Graphs
 Solutions for Students
 Static Graphic Images
 Step Functions in Answers
 Strings in Student Answers
 Tables in Problem Text
 Tables of Graphs
 Test Points for Formula Evaluation
 Text in Student Answers
 Textbook Specific Messages
 Tolerance in Numerical Answers
 Trig Functions in Degrees