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BMJ
09-30-2002, 10:33 AM
Er... verify something for me guys; Is the derivative of
sin(cos(x))equal to
-cos(cos(x))sin(x):confused:

Govtcheez
09-30-2002, 10:36 AM
That's not what I got - I got
sin(-sin(x)) * cos(cos(x))

I could be wrong, though.

BMJ
09-30-2002, 10:44 AM
Where did that extra sine come from?

Govtcheez
09-30-2002, 10:45 AM
Chain rule.

BMJ
09-30-2002, 10:49 AM
f(x) = sin(cos(x))

f'(x) = cos(cos(x)) * (-sin(x)) * (1)Right?

Govtcheez
09-30-2002, 10:51 AM
Um... Maybe. Like I said, I could be (and likely am) wrong...

Heh, 3 years of calc, and I can't remember a damn thing. Thank you, beer!

Govtcheez
09-30-2002, 10:54 AM
The answer I got from people that are better at this than me was -sin(x) * cos(cos(x)), so the same thing that you got.

Guess it's time to dig out that calc book again.

BMJ
09-30-2002, 10:55 AM
I just want to make sure I am remembering this stuff right so that I don't mess my entire week up as I go back trying to figure out what's wrong only to find it's this stuff :rolleyes:

BMJ
09-30-2002, 10:56 AM
Ok thanks Govtcheez! :)

ober
09-30-2002, 11:06 AM
working on... finding... Maple...

ok... I can't locate a free download of it anymore, but it's useful for checking your derivatives/integrals... sorry... you could look around for a copy of it tho.

BMJ
09-30-2002, 11:18 AM
I've never heard of it... does it work well?

Govtcheez
09-30-2002, 11:18 AM
ONce you figure it out, it's helpful. I never got the hang of it, though.

BMJ
09-30-2002, 11:20 AM
Hmmm... maybe I should write something to calculate derivative expressions like a TI-89 or Maple does :)

ober
09-30-2002, 11:37 AM
yeah, there's definately a learning curve, but when you can type in an equation and it spits out what you want.... you just can't beat it.

dbaryl
09-30-2002, 11:37 AM

BMJ
09-30-2002, 11:45 AM
Ok, then tell me mister TI-92... can you tell if the derivative expression for
y = sin(x^(1/2))+(sin(x)^(-1/2))is
[cos(x^(1/2))]/[2x^(1/2)] + 1/[2(sin(x)^(1/2))]:confused:

ober
09-30-2002, 12:24 PM
don't test the 92 or the 89... they are massive beasts of knowledge.

And if I was home or could remember anything from any of my calc classes, I'd do that on paper.

dbaryl
09-30-2002, 04:25 PM
Originally posted by BMJ
Ok, then tell me mister TI-92... can you tell if the derivative expression for
y = sin(x^(1/2))+(sin(x)^(-1/2))is
[cos(x^(1/2))]/[2x^(1/2)] + 1/[2(sin(x)^(1/2))]:confused: Yup, I can, just watch ;)

Attached you'll find a screenshot of an emulater TI-92 Plus with that problem. Seems correct to me :)

As you can see, there's a MINUS and not a plus in there.

Aran
09-30-2002, 05:58 PM
wow, that's one whacky emu, where'd you get it from?

dbaryl
09-30-2002, 06:05 PM
I think this link should do it:

http://www.ticalc.org/archives/files/fileinfo/84/8442.html

although I know I found it elsewhere. Emulates anything from 82 to 92+, with the right roms. The download on that page includes all of these.

I actually own a 92 (which I hate cause of it's size) as well as a 89 and 83. I think there's no real need for the 92 in any case, 89 can do it all just as well, except for QWERTY keyboard and some memory. Plus, an emulator doesn'r really care how much "memory" you have now, does it? ;)