Caveat Emptor: Negative Calculations with Fractions

[CNCDaveToo]

I've always appreciated how you could enter something like "1 2/3=" into a calculation field and have it automagically replace it with "1.66667". I'm constantly using this feature and praising the VCP team for it

There is a dark side to this feature that I hit recently. I entered "-1 2/3=" and since I'm so accustomed to using this functionality, I didn't bother checking the result. When things went sideways, it took a few minutes to find the culprit. Entering "-1 2/3=" results in "-0.33333" (and not the "-1.66667" that I had ass-u-me-d it would be).

I thought I'd found a bug, and reported it. Support replied that:

This is not really a bug, I am afraid that it is just how the math works with the notation.

To enter in 1 and 2/3 as a negative, you would need to enter in (1 2/3)*-1=

So it appears that in a calculation, a space is interpreted as a plus sign. Hence "-1 2/3=" is read as "negative one plus two thirds".

I get it, it makes the parsing dirt simple. It just caught me off guard and left me scratching my head wondering if that's hit me elsewhere that I haven't noticed (yet).

I just wanted to point this out to help others avoid the head scratching it took me to find.

[mezalick]

Good to know,
Thanks

Michael

[Leo]

Makes perfect algebraic sense, but to anyone that is a bit math challenged it is easy to imagine how that would seem a bit sideways.

Good on you for posting that.

[Rcnewcomb]

Honestly, I was surprised that they allow the space. I've always been entering

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1+5/8=

[adze_cnc]

Try: -1*(1 2/3) in the future.

[CNCDaveToo]

Honestly, I was surprised that they allow the space. I've always been entering

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1+5/8=

Of course. The even simpler solution becomes:

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-1-2/3

((I was getting hung up on the whole "multiply by negative one" aspect of it -- this is simpler))

-- Thanks RC