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submitted 13 hours ago* (last edited 13 hours ago) by soupborsh@discuss.tchncs.de to c/math@lemmy.world

Is there a way to make the function

f(w,t)=sin(wt)/w

defined at w = 0?

I want to achieve better numerical stability, and make it continuous everywhere.

Observation: Using lim~w->0~ f(w,t)

I know that at w = 0:

f(0,t) = t

Is it possible to improve this function? I would be really glad to know and why, how. Thank you in advance!

I really do not want to code in smth like: if w < 0.001 { x = t; }

Background notes: My equation also has constant v coefficient, but I removed it for simplicity. f(w,t)=v*sin(wt)/w

If I derived this correctly this should be x component of a motion of a car that rotates with rate w. It goes with const speed and const steer.

These are consts: v - speed, l - base length(dist from rear to front shaft), a - steering angle.

w(a) is defined idk if correctly. w(a) = (vsin(2a))/(2*l) I just logically added proportions, projections, imagining a rear wheel powered car. Put some values I am somewhat confident in, such as: w(0) = 0 w(π/2) = 0

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[-] carmo55@lemmy.zip 2 points 7 hours ago

If you want to do it yourself instead of using a math library, then my immediate thought is tp write out and calculate the Taylor series of your function. sin(x) is basically x +x^3 + x^5 +... with appropriate constants (look them up on wikipedia) so then sin(x)/x is the same thing but you divide all the parts by x so you're gonna have c + x^2 + x^4 + ... Now just add more parts in a while loop until the error term is small enough or you have spent some maximal number of allowed iterations and you're good.

[-] Buildout@lemmy.world 5 points 9 hours ago

People are being kind of rude, sorry about that.

I also think they aren't understanding your problem. You have a function f(w,t) = sin(wt)/w which is well defined everywhere (in the sense of limits at w=0 ), but for which the naive implementation (compute sin(wt), then divide by w) gives the "wrong" output for w=0 (an error instead of t).

Note that the function sin(x)/x has a name, sinc(x). Using this to rewrite your function gives f(w,t) = sin(wt)/w = tsin(wt)/(wt) = tsinc(wt).

Now you just need to find a quality implementation of sinc from a math library.

[-] gandalf_der_13te@feddit.org 2 points 12 hours ago

this seems like a standard problem. did you discuss it with your colleagues? alternatively, did you already ask chatgpt? where are you struggling?

[-] soupborsh@discuss.tchncs.de 2 points 11 hours ago

Hello. I am a school student making an open source robot car.

I did not ask my teammate, will do.

Btw there is our repository: (Currently there is no proper README.md, docs). https://github.com/XLNC-APEX/WRO_FE_2026_NATIONAL

You can see images and some steering, radius related experiment at my mastodon post. https://mas.to/@soupborsh/117011244080971088

I prefer to not interact with AI, that is why I am writing here to humans.

[-] gandalf_der_13te@feddit.org -2 points 11 hours ago

yeah and i prefer not to interact with people who seek help who apparently didn't put any work into trying to solve the problem themselves first

[-] Strawberry@lemmy.blahaj.zone 2 points 2 hours ago

Then don't comment.

[-] hendu@lemmy.dbzer0.com 2 points 12 hours ago

So... you want to define division by zero?

[-] soupborsh@discuss.tchncs.de 3 points 11 hours ago* (last edited 11 hours ago)

I thought maybe with some clever algebra or calculus the function can be transformed into function that has outputs equal to current's:

lim~w->a~f(w,t)

Since the limit (AFAIK) is defined everywhere.

Also maybe(idk) dividing really small number by other really small number is numerically unstable? I use f32(32 bit float) on microcontroller.

[-] hendu@lemmy.dbzer0.com 1 points 9 hours ago

Ahh yeah, I misunderstood what you were going for, sorry! Yeah, check out Buildout's suggestion!

this post was submitted on 01 Aug 2026
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