Problem with Patterns

Questions
1

I have the following code in my computational layer of a math response box. The lines that are not commented out currenly work, but don’t account for when the answer has an exponent of 0 and the student doesn’t enter the exponent (which is OK). So I attempted to fix that by entering commenting out the lines that are currently working and changing them to the lines commented out here. When I do that I get an error when entering a value with and exponent component. Even when my warning is commented out also. The message is that it cannont evaluate the entry. My project is [here]
(High School Placement Test Practice • Activity Builder by Desmos Classroom) The problem child is screen 7.

set up the pattern required

pattern = p.product(p.number,p.exponent(p.literal(“x”),p.integer))
matches = pattern.matches(this.latex)
warning: when not(matches) “Enter answer as Coefficient with variable x and exponent on the x variable.” otherwise “”

set up the pattern required REPLACED ABOVE 3 STATEMENTS WITH 6 STATEMENTS BELOW

#patternE = p.product(p.number,p.exponent(p.literal(“x”),p.integer))
#patternNoE = p.integer
#matchE = patternE.matches(this.latex)
#matchNoE = patternNoE.matches(this.latex)
#matches = matchE or matchNoE
#warning: when not(matches) “Enter answer as Coefficient with variable x and exponent on the x variable.” otherwise “”

separate the expression parts

coefficient = pattern.parse(this.latex).term1.numericValue
exponent = numericValue(pattern.parse(this.latex).term2.exponent.latex)

separate the expression parts REPLACED ABOVE 2 STATEMENTS WITH 2 STATEMENTS BELOW

#coefficient = when matchNoE this.numericValue otherwise patternE.parse(this.latex).term1.numericValue
#exponent = when matchNoE 0 otherwise numericValue(patternE.parse(this.latex).term2.exponent.latex)

2

I think one approach you might want is to define the different potential patterns that you are willing to accept and use the anyOf() pattern to verify the latex. Then, use a set of when statements to parse out the values based on the specific pattern that actually matched. I edited the middle part of the CL on slide 7 as an example. [Copy of] High School Placement Test Practice • Activity Builder by Desmos Classroom

Also, note that there is a formatLatex() function that does some basic clean-up of latex strings, removing 1s from coefficients and powers, changing + -3 to just -3, etc. This makes it a lot easier to generate nice looking random expressions.

3

Thanks. I’m just starting with computational layer stuff and desmos in general and this really helps.

4

No problem, happy to help. Once you’re working with patterns and randomization, you’re definitely in the deep end of the CL pool!

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5

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