Approximations of numbers are no longer equivalent

Staci Applegarth shared this problem 10 months ago
In Progress

In older versions of Geogebra, approximations (rounded values) of fractions were equivalent. However, now that I have updated older applets do not work. Works when the decimals are exact (1/2) but not when rounded (1/3). I have my rounding set to two decimal places currently, but it still isn't considering them the same. Example: https://www.geogebra.org/m/smGkFuFd

Comments (6)

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change expressions like a==b with abs(a-b)<=0.001 ie

In older versions of Geogebra, approximations (rounded values) of fractions were equivalent

I do not remember this issue

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Thank you for the idea!! I could go back and change them but I have a lot of applets, so to go back and change every single equality that worked before seems out of line. I use your inequality on new ones, but I would like my older versions to continue to work...

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I think it's more likely that there's an error in your logic - I think you can simplify this significantly

ch ≟ 0 ∧ r ≟ 1 ∧ d ≟ a_1 ∧ e ≟ a_2 ∨ ch ≟ 0 ∧ r ≟ 2 ∧ d ≟ a_1 ∧ e ≟ a_2 ∨ ch ≟ 0 ∧ r ≟ 1 ∧ e ≟ a_1 ∧ d ≟ a_2 ∨ ch ≟ 0 ∧ r ≟ 1 ∧ e ≟ a_1 ∧ d ≟ a_2 ∨ ch ≟ 0 ∧ r ≟ 3 ∧ g ≟ true
for example define check(x)=abs(ax+b)-c and then

correct = check(ans1)==0 && check(ans2)==0

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As I said, all of my logic worked fine up until I went back and tested it this week because I was having issues in creating new material. The problem is that if a=1/6 (which it approximates to 0.17) and a student types in b=1/6 (which also gets approximated to 0.17), it does not count a=b as true. This was not an issue in any materials I created before this last week, so I'm assuming it is an error in the update.

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Thanks, I see. That has changed (quite a while ago though). The simplest solution is to change the Input Boxes to the new "Symbolic" ones in Settings -> Algebra https://www.geogebra.org/m/dcek3wcq

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Ok, I will try that. Thank you.

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