This page is not created by, affiliated with, or supported by Slack Technologies, Inc.

## 2018-04-23

## Channels

- # beginners (27)
- # boot (8)
- # cider (17)
- # cljs-dev (8)
- # cljsrn (5)
- # clojure (56)
- # clojure-dev (34)
- # clojure-gamedev (4)
- # clojure-italy (32)
- # clojure-nl (22)
- # clojure-poland (3)
- # clojure-russia (17)
- # clojure-spec (31)
- # clojure-uk (48)
- # clojurescript (47)
- # core-async (41)
- # cursive (13)
- # datomic (22)
- # emacs (9)
- # figwheel (7)
- # fulcro (18)
- # graphql (3)
- # hoplon (15)
- # jobs-discuss (38)
- # keechma (1)
- # luminus (10)
- # off-topic (42)
- # onyx (8)
- # overtone (3)
- # protorepl (5)
- # re-frame (42)
- # reagent (6)
- # reitit (3)
- # schema (4)
- # shadow-cljs (39)
- # slack-help (5)
- # spacemacs (8)
- # specter (1)
- # tools-deps (36)
- # uncomplicate (9)
- # vim (34)

working on MIT's 6.006 on my own as a mooc... was stuck on this part: https://cs.stackexchange.com/questions/41588/do-not-understand-why-log-n-onc-for-any-c0

tried the above in wolframalpha. at some value of k, say 50, there will always be some value of n where the inequality is true. when n gets bigger, the inequality is no longer true

I don't understand how log (n) = O(n^c) in this case. anyone understands this?

did you read the answer to the question above? there's some confusion of terminology. `log(n) is-element-of O(n^c)`

yup, but still, for a value of k, say 50, once n is 10^16, the inequality fails, so for k = 50, I can't find a n_0 such that for n>=n_0, log n <= k n^c

so lets ignore scaling and maybe drop the exponent a little bit

```
(let [n 10e15]
(prn (Math/log n))
(prn (Math/pow n 0.1)))
36.841361487904734
39.810717055349734
```

with just an exponent of 0.1 it takes to about 10^15. so for your example here with the escaling and the exponent, maybe try 10^1000000000

if you change the exponent to just 0.01 you can see how much you chop down that number and consequentially push out that changeover spot n_0

I see!

so i just got tricked by the plots

although in clojure the 10^16 works for me:

```
(let [n 10e16]
(prn (Math/log n))
(prn (* 50 (Math/pow n 0.0000001))))
39.14394658089878
50.00019572011597
```

if i twiddle the constants a bit, the lines actually intersect twice

was seeing this and never thought it was possible that it would intersect again

Trying to find the best place to post a blog

it's clojure related, and wondered whether this channel is the correct place

any help would be much appreciated

Hi @functionaltom, you could post into *#news-and-articles*

Ah, I see someone beat me to it

thanks for the heads up though!

It's easier to ask forgiveness rather than get permission 😛

If it's Clojure related, it doesn't seem offtopic. *#clojure* ?

thanks,

In WebGL, is there a way to query the runtime for "maximum # of vertex buffer objects" ? I'm not asking for the largest # of floats a single VBO can have; I want to know how many VBOs total I can have.

is there a limit?

According to some email list, the limit on buffer objects is the lower of: 1. 2^32-1 2. when you run out of GPU memory

which really means #2, since if you assume floats or ints for verts, and you assume one triangle per VBO (don't do that, it's a horrible idea), you'd need 206GB of GPU memory to handle it all

eh, 103, since it's ^32-1

is there a way to sorta do GPGPU in WebGL? I need a way to setup a shader where
input ` vbo, output `

vbo OR
input ` texture, output `

texture
and just run the shader (everything stays in GPU memory)

You want to read up on render to texture options in webgl

@tbaldridge: so the high level idea is to setup the computation in 'stages', where each 'stage' is rendering a scene to texture ?

@qqq pretty much textures look a lot like arrays inside the shader, and you simply read from one to output the pixel of the other

turning off stuff like 3d projections and the like so you can get a 1:1 mapping from pixels in the input/output to the array locations in the textures

I wouldn't be surprised if they start implementing it once later wasm specs expose the DOM