"Phil Hobbs" wrote in message
m...
On 12/12/2013 10:27 PM, Tim Williams wrote:
Try regular hyperbolae. The derivatives exist... just take care not to
divide by zero (which can happen with tanh too, and probably at analogous
points, for analogous reasons).

Division by zero computing tanh of a real number? That would take talent.
Care to elaborate?

Maybe it was atanh, but it's not the function of a real number, it's the
derivative that causes problems. Certain people here swear by this for
continuous limiter functions in SPICE, but I've found they can go batty
rather often.

Incidentally, The Internet doesn't know that degenerate circuits aren't the
only condition that can create singular matrices.

Tim

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