Nonlinearfit (real function with complex entries)
- To: mathgroup at smc.vnet.net
- Subject: [mg50003] Nonlinearfit (real function with complex entries)
- From: alex_punnoose at yahoo.com (Alex)
- Date: Wed, 11 Aug 2004 05:52:57 -0400 (EDT)
- Sender: owner-wri-mathgroup at wolfram.com
Hello,
I have a real function whose individual terms are complex
(they sum up to a real number). The functions involved are
digamma functions and trigonometric.
When I use this function in NonlinearFit, I get the following
error:
FindMinimum::"fqnum": "Objective function or gradient is not real
General::"stop": "Further output of FindMinimum :: "fqnum" will be
suppressed during this calculation."
I guess the problem is that the function is real only upto an
infinitesimally small imaginary part ( of the order 10^{-16} ) set
by the machine accuracy.
I tried the following: Chop, ComplexExpand, Re, defining the
derivates explicitly and then chopping it and a lot of other things.
Could someone out there please help me?
Thanking you in advance - alex