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neodymDNB · Post by **neodymDNB** » Tue Jul 26, 2016 1:21 pm

I just finished reading the book Digital Signal Processing by Steven W. Smith.I feel I have pretty good understanding of basics but there is big problem

I stopped learning math when I was 11 years old,but I was going to school 1 year latter,I have literaly mathematical knowledge of 10 year old,basic arithmetic is only thing I know.

I am trying to learn more from youtube videos but I dont understand the equations so I cant progress.Please can you recommend me some youtube channel or online site to learn the mathematics I will need for programing FFT and FIR filters in c++?

what I know so far : X = input ... Y = output ... n = sample ... h = impulse reponse ... f = freqency response ... * = convolution

stratum · Post by **stratum** » Tue Jul 26, 2016 1:29 pm

That one is not really a math heavy book. These should be adequate:

http://spgia.gmu.edu/current-students/m ... -tutorial/

https://www.mathsisfun.com/algebra/trigonometry.html

https://www.mathsisfun.com/calculus/limits.html

https://www.mathsisfun.com/calculus/int ... ction.html

https://www.mathsisfun.com/calculus/der ... ction.html

https://en.wikipedia.org/wiki/Complex_number

https://en.wikipedia.org/wiki/Euler%27s_formula

neodymDNB · Post by **neodymDNB** » Tue Jul 26, 2016 2:02 pm

oooo yes! thank you! going to read everything you posted

edit: I am looking at that Trigonometry "unit circle" animation,so 2π ( two pi ) means full cycle of wave? ( sinewave for example )

stratum · Post by **stratum** » Tue Jul 26, 2016 2:04 pm

This "I don't know enough math" problem is similar to "I don't know how to read sheet music" problem.

The fact is that most people actually know how to read sheet music. It's trivial. But I cannot play a simple song on a piano without memorizing it first by just looking at its notation... The difference is fluency in reading sheet music.

eegee · Post by **eegee** » Tue Jul 26, 2016 5:11 pm

A lot of great math concepts in Better Explained. Here is one on Complex Numbers for example, but I encourage you to explore other topics: https://betterexplained.com/articles/in ... x-numbers/

matt42 · Post by **matt42** » Tue Jul 26, 2016 5:34 pm

I'd recommend Basic Engineering Mathematics It doesn't assume GCSE level maths (don't know where you're from, but basically that's the exam taken at 16 in the UK), so probably a suitable starting point from what you said.

It starts at the very basics, basic arithmetic, percentages, fractions and builds up to calculus. With section on algebra, manipulating equations, trig etc. As its for engineering most of the stuff will lead on nicely to DSP.

I haven't read this book, but one of the authors others on engineering maths and found it very helpful.

stratum · Post by **stratum** » Tue Jul 26, 2016 5:50 pm

I am looking at that Trigonometry "unit circle" animation,so 2π ( two pi ) means full cycle of wave? ( sinewave for example )

Yes that's the period of a sine function. There are other possibilities, for example many people take 1 to be the repeating period of a saw function (i.e. interval 0..1). Since saw(x) is not a commonly defined function they can assume whatever they want. In case of sin(x) almost everybody assumes x is in radians, thus 2pi is its period. In highschool that was degrees (pi radians = 180 degrees), instead.

JCJR · Post by **JCJR** » Tue Jul 26, 2016 8:34 pm

Modern math teaching even in science and engineering, as best I can tell, seems to leverage the power of computer math programs. In my school days they leveraged the power of slide rules, log and trig tables. Or a little later leveraging the power of electronic calculators.

Back in the pre-calculator stone age, there were different courses-- For instance "liberal arts calculus", "engineering calculus", "math major calculus". I took the engineering calculus which was rather unpleasant and painful involving problems with nasty answers requiring many pages of paper to solve. Sis took "liberal arts calculus" which she loved. It covered similar concepts, except the example problems were easy to solve and had neat tidy answers. Dunno what a rigid "math major calculus" course would have looked like back then. Maybe similar to the "liberal arts calculus" but causing more brain damage.

It was similar with other math courses. "Statistics for Social Sciences" was simpler than "Statistics for Business" was simpler than "Statistics for Economics." And then "Statistics for Math Majors and Physicists" was a brain-buster.

Even with the assistance of computer math programs, some practice in solving the problems would be helpful. At least knowing how to run the damn programs. It is hard to have enough discipline to spend months or years working numerous throwaway learning problems to get expertise in the mechanics, except in a class with grade pressure.

Some kind of semi-formal study method with homework problems, computer math program assisted, might be the "easiest path" nowadays? It is just easy to watch a problem being solved and believe that one has learned how to do it, until one has to solve a similar problem from scratch with no assistance. That's where the practice comes in. Its also good to have easy access to somebody who will answer lots of dumb questions.

stratum · Post by **stratum** » Tue Jul 26, 2016 9:28 pm

Every once in a while I run wxMaxima thinking that this time I'll learn this thing... and then I cannot find enough time and leave it and forgot what I had learnt during an hour or so hacking. Math is a thing that requires routine practice, like programming. Otherwise, the result becomes very much like what most people can do while reading sheet music, they would know reading sheet music really is an easy thing, almost to the point of being trivial, but that does not mean they can make effective use of it.

BITWORD · Post by **BITWORD** » Tue Jul 26, 2016 9:34 pm

Khan Academy is a great place to polish up on selected areas - or just start your math education at where you left off - and it's interactive - and FREE - They have videos on YouTube too (last I looked).

https://www.khanacademy.org/

JCJR · Post by **JCJR** » Tue Jul 26, 2016 9:49 pm

Hi Stratum

I don't remember much math. Most likely to remember stuff I actually used.

I like your sheet music analogy. I easily sight-read playing from chord charts or lead sheets because I used em nightly for years. But as you describe, I have to painfully work thru polyphonic two stave piano music because it never got practiced sufficiently to acquire skill in quickly recognizing "numerous simultaneous notes".

stratum · Post by **stratum** » Tue Jul 26, 2016 11:00 pm

I like your sheet music analogy. I easily sight-read playing from chord charts or lead sheets because I used em nightly for years. But as you describe, I have to painfully work thru polyphonic two stave piano music because it never got practiced sufficiently to acquire skill in quickly recognizing "numerous simultaneous notes".

This is pretty much like what happens after reading "Digital Signal Processing by Steven W. Smith". All the other dsp books look like sheet music written in the bass clef, while you can only read the treble clef fluently, but it becomes obvious that those cumbersome math formula derivations are just that, formula derivations. But one fact remains, that is the way that job is done, unfortunately. Yet on the other hand, it's also clear that programming something like this does not require any of it: https://www.youtube.com/watch?v=Aau2g5_ytSY (I don't know whether the author would agree, it's a pretty nice plugin, BTW (version 2 that is, the first one in the video has a bug in the oscillator)).

I dont understand equations...