Feedback Overview - mkraska/meclib GitHub Wiki

Here we collect procedures for creating feedback in STACK questions (with or without MecLib).

Feedback for numeric input

• fb_number generic feedback for numeric input. Function is obsolete, use fb_unit.
• Value Less or Greater than Expected. Function is obsolete, use fb_unit.
• Feedback on Numeric Precision

Feedback for numeric input with and without units

• fb_unit generic feedback function for unit input
• Correct base units? (is done with UnitRelative and Co)
• Is the value provided strictly numeric (not an un- or just partly simplified expression)? (how to do this?) -> for numeric input only, you have the extra options intnum and floatnum
• Value Less or Greater than Expected
• Mantissa Check Is the result off by an order of magnitude?
• Check of Sign Is the sign correct? This is less trivial than it seems.
• Zero values with units How to handle unit inputs where the result could possibly be zero?
• Exclude unwanted units E.g. Hz for angular velocities or J for moments

Feedback for symbolic input

• fb_vars Missing and spurious variables and check for correct coefficients
• Correct Coefficient of Variables
• fb_dim correct dimension
• off by a numeric factor? (note, expressions aren't necessarily products)

Feedback for interactive graphical input

• Sums of Forces and Moments
• Feedback for Free Body Diagrams
• Values and Slope of Splines
• Data Extraction
• Logics of Reaction Assignment

Other special purpose feedback

• fb_HAG feedback rectangular triangles (hypothenuse too short or too long)
• Matrix Feedback

Input and validation issues

• Impossible input: F_1x is not allowed (STACK issue #792)
• ambiguous validation: x0 and x_0 (forum discussion). Recommendation: always use x_0 in question variables and in input instructions. Eventually forbid the underscore-less versions at input level.
• ambiguous validation: f(x) and f*x (forum discussion)
• ambiguous validation: a.b and a*b (forum discussion)
• wrong validation: 1 *N as 1^N (forum discussion)
• compound symbols like in input and validation (forum discussion)
• display of expressions (formatting), forum discussion
• handling of derivatives in input (forum discussion)
• input of pure integers or floats (forum diskussion)
• refusal of -1*cm in "units" input. Use stackunit(var, unit) instead of var*unit in the model answer field to avoid this. (github issue)