If

F(x,y,z) = sinyi + (xcosy + z )j + yk

find a function f (x,y,z) such that

F = grad f

how would you go about solving this one?

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- Mar 18th 2011, 05:05 PMheatlyVector Field
If

F(x,y,z) = sinyi + (xcosy + z )j + yk

find a function f (x,y,z) such that

F = grad f

how would you go about solving this one? - Mar 18th 2011, 06:24 PMalexmahone
- Mar 19th 2011, 05:29 AMHallsofIvy
Perhaps a touch simpler: from we get

Now differentiate that with respect to y: so that . That tells us that . f(x,y,z)= x sin(y)+ A(y,z)= x sin(y)+ yz+ B(z).

Differentiating with respect to z, so B'= 0 and B is a constant.

f(x,y,z)= x sin(y)+ yz+ B

Alex Mahone left off the constant because the problem only asked for "a" function having that gradient. - Mar 19th 2011, 06:42 PMxxp9
Let me add one:

let . It's easy to verify that . So F is really conservative and the line integral of doesn't depend on the choice of path.

For any point , Choose a path C with the following 3 segments:

I: from (0,0,0) to , along the y-axis

II: from to , along the direction of z-axis

III: from to , along the direction of x-axis

The

- Mar 20th 2011, 02:51 AMheatly
Thanks everybody for your help.

- Mar 21st 2012, 11:49 PMJohnMbostonRe: Vector Field
I'm new to the forum.

Question: Can you please explain yow are you pasting in these nice italicized vector function equations?

I've fooled around with typing in Word and doing print screen paste or upload a jpeg but these don't seem to work.

Thanks. - Mar 22nd 2012, 01:21 AMalexmahoneRe: Vector Field
- Mar 22nd 2012, 02:58 AMblingRe: Vector Field
- Mar 23rd 2012, 12:50 AMJohnMbostonRe: Vector Field
Thanks for the tip. The Math Input Panel works for me in, say, MS Word but I cannot make entries into a Forum message box. If I copy and paste from Word I lose things like the right-pointing vector line symbol above capital F or the hats above i+j in a vector function. Suggestions?

(Sorry, I'm an email guy, not a whiz at online forums, but I'm learning.) - Mar 24th 2012, 02:50 AMblingRe: Vector Field
correct even i tried it but doesnt work. sorry mate if i find something ill post it