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Hello!

I would like LimeSurvey to automatically calculate the result of a mathematical formula as shown below, using ExpressionScript:
y = -0.0011x^3 + 0.061x^2 + 2.0253x + 1.1913, where x is the output of a previous question (let's call it Q1.value).

I have created a new Equation question, and have used the following code:

{sum((-0.011*(pow(Q1.value,3))),(0.061*(pow(Q1.value,2))),(2.0253*(Q1.value)),1.1913)}

but the output/evaluated expression is nonsensical (totally different from expected.

What am I missing here, or have I evaluated something wrongly?

Thank you!

Did you try to break your formula down to see where things are going wrong? This way you can see what works and what doesn't.

Maybe it makes sense to have seperate equations for the bit and calculate each seperately and only join the bits at the end.

Another thing: Q1.value references the assessment value of a question, not the value someone has put into the box.this might be what you want to do, but it also might be wrong. So give us some more info. And ideally provide an lss file with just the relevant questions, so we can see what yo do and play around (copy the survey and delete stuff or create a new dummy survey. No lsq or lsg files please)

I do not see any issue
Maybe the  wrong use of the property ".value".
As you read here
[url] www.limesurvey.org/manual/ExpressionScri...#Access_to_variables [/url]
the assessment value for the question if it is relevant (otherwise blank), or the text value if it is not a coded question

We do not know the source of your x (type of Q1)

 
Here you may use ".value" or not, no difference, as it is a not coded question.

But if the source of your x is a coded question, e.g. list(radio), you must not use it if you do not use assessment values.

Joffm