## What makes linear transformations more important than other types of transformations?

It just seems odd that Linear Algebra stresses them exclusively when other non-linear transformations can still be extremely helpful. In stuff like machine learning non linear kernels help us see non linear patterns such as circular, logarithmic, exponential, quadratic, etc. Is there an analogous math to linear algebra that focuses on non linear transformations?

submitted by Nevin Manimala Nevin Manimala /u/Ludwig0

## Word Problem about Geometric series

Help! I’m studying for a quiz and I saw this question in my book.

A patient has an infection that, if it exceeds a certain level , will cause the patient’s death. He is given a drug that will inhibit the spread of the infection. The drug acts in such a way that the level only increases by 65% of the previous day’s level. On the first day, the level of infection is measured at 450. The critical level of infection is 1,280. Will the infection reach its critical level?

submitted by Nevin Manimala Nevin Manimala /u/androthemofo

## Does this prime number translate into binary of DVD copyright removal software?

Hello, I have just been reading about illegal prime numbers and I am not 100% sure I am understanding this correctly,

apparently https://en.wikipedia.org/wiki/Illegal_prime states that ” Its binary representation corresponds to a compressed version of the C source code of a computer program implementing the DeCSS decryption algorithm, which can be used by a computer to circumvent a DVD’s copy protection”

and this is by pure chance? it just happens to represent the binary of this source code in total? Not just one small part of it?

This seems like the chances of this is insanely tiny, how would I work out the probability of this happening? To me it seems almost impossible.

edit: http://primes.utm.edu/glossary/page.php?sort=Illegal it seems the code existed, then someone worked out that it could be translated into a prime number through some various means. But it still seems very crazy that this can work at all.

submitted by Nevin Manimala Nevin Manimala /u/Togglee

## Is there a simple formula to approximate the average of some number’s divisors?

Using the divisor function, is there a way to approximate sigma_1 (n) / sigma_0 (n)?
Or at least an average of that for all natural numbers less than or equal to x?

submitted by Nevin Manimala Nevin Manimala /u/ddotquantum