What is the first derivative of this function? I am trying to implement a computer simulation of the algorithm described in this paper. I need to find a root using Newton's method. The problem is that I need to know...--prophetes.ai

What is the first derivative of this function? I am trying to implement a computer simulation of the algorithm described in this paper. I need to find a root using Newton's method. The problem is that I need to know the derivative of the complex modulus function and my math knowledge is not helping me a lot. The function is described at p. 4 of the PDF file: ![enter image description here]( I mention that the function contains complex values, excepting the absolute values (|.|) and lambda. Can anybody help me with the first derivative of this function?

Don't bother with Newton's method. You need to choose an initial $\lambda$, so choose two and use the secant method.

A good discussion is here:

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