# Math tip for all ya'll

So while hammering away at my sphere issues I needed a formula to tell me what a particular point on an edge would be numerically at any given point. The issue was that the numbers are increasing at a weird amount every time and it’s been ages since I’ve done calculus. But then… I remembered reading about Wolfram Alpha. Decided to give it a whirl and blam! Got the equation I needed.

So the sequence I needed an equation for I determined by literally drawing out the shape I wanted and numbering the points how I wanted them numbered. For 1 sequence I had this number sequence:

0, 2, 5, 9, 14

If you copy that sequence into the search here: https://www.wolframalpha.com/ you get a neat page back telling you all sorts of interesting things about that sequence. But… for my case the interesting bit was right at the end where it spit out the equation:

a = 1/2(n - 1)(n + 2)

So “n” is the position of the number in the sequence and “a” is the value. And yes. This equation is accurate (I tried it out by hand for the next 3 points in the line just to be sure).

So ya! There’s my tip! If you need some help figuring out some math give Wolfram Alpha a shot! It’s scarily easy to use.

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wow… that’s awesome

Ya. I have like another 3 or 4 equations I was going to need to figure out to make some complex shapes and was not looking forward to diving into the deep end of crazy math.

I didn’t quite understand what was your issue, but +1 and bookmark for linking this witchcrafts searchengine.
I’m sure one day i will need it.

What I was using it for was subdivided triangles. If I subdivide a triangle say 2 times you get a triangle that looks like this

``````        0
/ \
1---2
/ \ / \
3---4---5
/ \ / \ / \
6---7---8---9
/ \ / \ / \ / \
10--11--12--13--14
``````

I needed to find a simple way to find the id of the point on the right edge 1/2 way between point 0 and point 14. The other equation was for the same thing but on the left edge.

In the end this is to make sure all points are well organized so when I make quads out of paired equilateral triangles I don’t have to go hunting for ID numbers. I just math it up.

3 Likes

So many times I tried to figure out a formula from a series of numbers… and I suck so terribly at math… this thing is going to change that…

1 Like