No I didn't. The simplest refute to your answer is that your J[1] is -2*params[0]*(xx*params[1]-params[1]^2). How could there be a term with params[1]'s quadratic in the derivative if the original function is a quadratic function? On 6/25/07, Christian K <ckkart@hoc.net> wrote:
Lin Shao wrote:
## Now define my Jacobian def Jacobian(params,xx,yy,mode='col'): J = N.empty((len(params),xx.size)) J[0] = (xx-params[1])**2 J[1] = -2*params[0]*(xx-params[1]) shouldn't that be -2*params[0]*(xx-params[1])*params[1] ?
I think I was right. Think about what's the derivative of -x^2 -- it's -2x
you forgot about the chain rule .
Christian
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