Using of abs fonction

Hi Commcare Team,
I want to have the difference between the measure of 2 sizes, size 1 and size 2.
I created a hidden field that calculates the difference between the 2 sizes. size 1 can be less than or greater than size 2.
To have the result in absolute value, I add the abs fonction in the hidden value to calculate the difference between the 2 sizes like this: abs(#form/taille_mesure_1 - #form/taille_mesure_2)
After I display the result to show in a label field for the mobile users, but it’s not work.
Thanks for your help once again!

What do you mean when you say it doesn’t work? Does it not return a positive result? No result at all? What are the values you’re testing with? Do you get an error? What’s the error message?

Thanks Ethan for your avaibility.
After app updated and sync with the server abs and round founctions work wonderful.