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UPinar

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Summation Notation

I decide to learn Artificial Intelligence with C++. When i was reading some blog's about AI, i found out that i need to learn some mathematics. Then i started searching about what i need to learn.

I found a blog post about what math needed to learn. Here is the link.

All the Math You Need to Know in Artificial Intelligence


In summation subject i started watching a video which is

Video is good to see what is happening in summation notation but i need to find out the proof of these formulas.

Summationformulas


forI

Sum of the First n Positive Integers are well explained in here

sumFirst1

sumFirst2

We add all the number from (1 to n) [1 + 2 + 3 + ... + (n-2) + (n-1) + n] first. Then add all of them from (n to 1) [n + (n-1) + (n-2) + ... 3 + 2 + 1] second. If we add these two sums bottom to bottom we get values (n + 1) summed for n times (n + 1) * n. Because of we use sum of all the values for 2 times (first and second), we need to divide the whole sum by 2.[(n + 1)* n] / 2. That is okay and the image below explains it beautifully. Learning from the image is a better way i guess so i started searching for an image solution for i(square).

firstSumImage


forISquare

Gaussian proof for the sum of squares?

I found out an answer here

summationSquare

The image above, we are drawing 3 triangle starting from 1 to n. All triangles are starting from different corners.

  • (1^2) = 1 (Using 1 for one time in triangle)[1=1]

  • (2^2) = 4 (Using 2 for two times in triangle)[2+2=4]

  • (3^2) = 9 (Using 3 for three times in triangle)[3+3+3=9]

  • (n^2) -> (Using n for n times in square)[n+n+...+n ntimes=n^2]

So it is like adding whole sum for 3 times like the first example.

When we add all the values at the same place in all triangles, we get a (2n + 1) valued triangle.

  • First Row -> (1 + n + n = 2n + 1)

  • First Column Second Row -> (2 + (n - 1) + n = 2n + 1)

Now we need to find out how many times we are using (2n+1) value in the last triangle. To understand it easily we can change all numbers to 1.

totalTriangle

This is exactly what we do in first example. Sum of the values from 1 to n. The answer is [(n + 1)* n] / 2. We use (2n + 1) for [(n + 1)* n] / 2 times.

So now we have a triangle which have (2n + 1) value for [(n + 1)* n] / 2 times and this triangle created by 3 same triangle so the result of [(2n + 1) * ((n + 1)* n) / 2 ] needs to be divided by 3.
Final result is [((2n+1) * n * (n+1)) / (2 * 3)].


I could not found any answer like this for cube.

If you find out, let me know.


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Have a good day!

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AngieNabors

Embarking on an exciting journey into Artificial Intelligence with C++ is a fantastic choice! It's not just about coding; understanding the foundations is key. Betbook 247 com login