[微積]求兩題gradient分析?
(1)Run gradient descent, staring at (-0.8,-0.8)
with "alpha"=0.2 and 139 iterations, for the surface
z=f(x,y)=exp(x*y) / (exp(x^2*y^2) +1), -3<=x<=3, -3<=y<=3
Q1:Explain why the algorithm stalls and does not descend further?
(2)Run gradient "ascent", staring at (-0.6,-2.3)
with "alpha"=0.1 and 529 iterations, for the surface
z=f(x,y)=(y^2*x^(2/3))/x^2+y^2+1, -3<=x<=3, -3<=y<=3
Q2:Explain why the algorithm zig-zags around the optima?
只會用matlab跑出圖形,但不知道怎explain有無高手可幫忙!感恩!
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sorry,(2)因該是ascent,f(x,y)=(y平方*x平方開三次方根)/(x平方+y平方+1)
再麻煩幫我解答
※ 編輯: jolin19 (151.181.36.98), 09/15/2017 23:05:44
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