Wrong percentage addition and subtractions

[bhavin192]

Steps to reproduce

Do calculations of type:

• 120+5%
• 120-5%

Expected behavior

It should be 120 + (120x5%)

• 120+5% = 126
• 120-5% = 114

This is how it used to be in previous versions. And other applications also calculate it this way.

Actual behavior

These result in:

• 120+5% = 120.05
• 120-5% = 119.95

Calc You version

3.1

Android version

Android 15

Other details

Acknowledgements

• I have searched the existing issues and this is a new ticket, NOT a duplicate or related to another open issue.
• I have written a short but informative title.
• I will fill out all of the requested information in this form.

[Bnyro]

Personally I'd expect the opposite behavior.

For example, if I want to do some statistics like P(rainy) = P(rainy|wet floor) * P(wet floor) + P(rain|NOT wet floor) * P(NOT wet floor) = 50% * 0.3 + 10% * 0.7, I definitely want the plus sign to add the absolute percentages and not add them relative to the first summand, otherwise my result would be wrong.

You can simply achieve your expected behavior by doing 120 * 105%.

[m3thm4th]

@bhavin192 is absolutely right and what he described is the behavior of every calculator, this is the first time I've seen something like this as a wilful behavior of a calculator. Why would you ever want the percentage to be applied to 1 automatically? It makes no sense.

50% * 0.3 + 10% * 0.7

This doesn't make any sense, you just type .5 * 0.3 + .1 * 0.7 to do this, very easy, and if it's a more challenging number, like 77.684% it's easy to type x - 77.684%, but it's way harder to do x * (100-(100-77.684))%, whereas the calculation in your example would be very easy like .77684 * x

@Bnyro Would you please reconsider this issue?

[Bnyro]

I'm not interested in working on this, but I'll reopen it if somebody else wants to make a PR.

Fyi, this isn't really possible with the way our math parser is implemented, so it would require to rewrite large portions of the code.