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Tzad July 14th, 2015 12:13 PM

Gradient Question
 
So I don't get what I did wrong either.
fx(1.3)=-6x=-6(1)=-6
fy(1,3)=-6y=-6(3)=-18
Gradiant <-6,-18>
Length is Sqrt((-6)^2+(-18)^2)=Sqrt(360). Unit Vector =1/sqrt(360)<-6,-18>
b)
I'm not sure if we find the Length of the Gradiant Vector of length of the Unit Gradiant Vector
Gradiant <-6,-18>
Length of Gradiant: Sqrt(360)

What am I doing wrong?
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http://i.imgur.com/i4jqXq8.png

Tzad July 14th, 2015 01:18 PM

Nevermind.

The question asks for the fastest descent (slope is negative), while the gradient always gives the fastest ascent (where the slope is positive. I needed to multiple the vector<-6,-8> by negative one to get to a unit vector of 1/sqrt(360)<6,18> and hence a fastest downward speed of -sqrt(360).

Sorry for the trouble. You can close the thread.

From,

Tzad


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