Hi! I’ve this expression 6:2(2+1) and, I think, the result is 9. About wolfram’s opinion, the result is 1. If I put 6/2(2+1) the result is 9.. so the 6:2(2+1) is like a proportion?
What does 6:2(2+1) mean? What operator is : supposed to be? what is the result of 6:2 supposed to be? I do not think I’ve seen : used in Mathematica before and I have 10.3. I’ve seen it in Matlab though.
The operator “:” is a less commonly used notation for division. Very few people are aware of it outside the countries where it is used.
Yes, Wolfram|Alpha is treating it as a ratio. The difference between your result and Wolfram|Alpha’s result is opinion over order of operation.
My recommendation is just not be ambiguous about the order of operation and to use “/” instead of “:”. Using colon for division is pretty rare.
I assume that you are putting this into WolframAlpha. And I assume that your colon is meant to indicate a ratio. If so, the reason why you get the answer that you do is because of the precedence of how WolframAlpha is interpreting your expression. It is interpreting it as the ratio between 6 and 2(2+1) which indeed is 1.
http://www.wolframalpha.com/input/?i=6%3A2%282%2B1%29
If you us brackets to indicate that you in fact want the result of the ratio between 6 and 2 then multiplied by (2+1) then you have to put brackets around the 6:2 as in (6:2)(2+1) which is indeed 9
Hi,
I don’t think that this is a Mathematica question. Mathematica does not evaluate that input:
It appears to be a WolframAlpha question.
You can get the subpod from the output:
WolframAlpha["6:2(2+1)", {{"Input", 1}, "Content"}]
Now, if you apply TreeForm to it you see how this is interpreted:
TreeForm[%]
If you look at the lower left of the tree, you will see how this input is interpreted and evaluated.
Cheers,
Marco
PS: David & Sean, sorry for the cross-posting, I was apparently typing up when you replied…
You beat me to it as I was typing 
Though it gets used as the “quotient-by-ideal” operator in algebraic geometry.
And there is it’s appearance in the famous Fitzwillian Inn rebus: (!)
im = Import[“https://www.cardcow.com/images/set190/card00288_fr.jpg”]
Unfortunately this one has been replaced of late by:
newimage =
Import[“http://www.minervaclassics.com/railroad/WEAFitz03b.jpg”]
I will not actually show the newer one. Out of protest, I guess.
Here is a coding challenge. One can zoom in, more or less, on the (original) rebus from the picture as below. But I’m sure it could be done much better, possibly by some rotation magic to move the right side more forward for example.
im2 = Sharpen[ImageResize[ImageCrop[im, {130, 90}], {300, 300}], 15]
In Germany I would always have used : to mark division; perhaps Leibniz’s influence. Here in the UK it is usually / , I guess.
There is a nice summary of mathematical symbol use here.
Cheers,
Marco