Islamic Forum

# Help Needed !

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need help with this..

t is a constant, tau (funny looking t) is the variable we are trying to integrate..

i know we have to use some cos - sin identity but i'm not sure..

:D..

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WOW I'm SO glad I don't have to do that stuff anymore. You need a TI89 calculator or one that can do integration for you. I'll look for the identities but it's been awhile :D

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AS

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Where x=tau

Ha Ha...honestly :D

Try this site to confirm :D :D

So yeah, plug in your limits and run that *#*#

:D

AS

PS It's saturday and you're doing intense integration...you must be either an engineer or a Muslim :D

Edited by Allah's Slave

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thanks.. but thats nasty man..

PS It's saturday and you're doing intense integration...you must be either an engineer or a Muslim
so what if its sat nite ?? lol and yes i'm both.. but you knew that already mr.T :D

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thanks.. but thats nasty man..

You're welcome. Did it work after you put in your limits?

There's not much I can do about the rules of calculus for you :D :D

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AS

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... lol and yes i'm both.. but you knew that already mr.T  :D

Ha Ha I was jokin akhi!!!

Lemme know if it worked!!!!!!

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AS

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somethings wrong man..

well tuesday we'll find out or if not then tomorrow morning :D i'll give this a try again..

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Actually bro AS.. do you know convolution ?? thats what i'm trying to do..

g(t) = sin(t) u(t) convolute sin(t) u(t)

u(t) = step input i.e. u(t) = 0 for t < 0 & 1 for t >=0.. in other words the u(t) function is just making sure the sin functions start at time t = 0 and not in the past..

so the way you solve this convolution is by this:

g(t) = Integral from 0 to t of sin (tau) * sin (t-tau) dtau

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Then Try

-cos(x)*[cos(t)cos(x)+sin(t)sin

x)] from your limits between 0 and t

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AS

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okay thanks.. i'ma look into it..

darn.. this used to be easy for me but i've been away from school for 2 years :D.. thanks bro..

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I don't believe I have done convolution, at least I don't remember the name. However, after looking at:

the f's and g's look familiar. I remember doing some f(g(x)) stuff before but I dont think it was convolution.

I'm off to isha at the masjid inshallah but if you're still stuck tomorrow I'll try to help. Keep me posted.

I'm out for now. PEACE!

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AS

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...this used to be easy for me but i've been away from school for 2 years ...

Seriously, I know all about it. I had all my calc the 1st 2yrs of school and then we only used the simplest equations for the rest of it. When I took the FE exam the integration was HARD!!! Especially with the kindergarten calculator :D

It's ok, like our other topic, in the real world you can use computer tools to do this stuff...as an engineer :D

"optimizing for time"

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AS

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so i'm guessing there are no other communication engineers here huh ??

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:D did you ever get it figured out? Please! I'm DYING to know :D

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AS

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its due thursday..

but today i'm meeting with some people.. will let you know AS..

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yoh bro i feel stupid..

all we had to do was use one of those dum trig identities to get rid of the sin sin thing.. so we would have 1/2 sin + something else sin and now this is easy to integrate..

i feel stupid.. esp since it was a girl who showed me it :D ..

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