Converting Polyfit exponents to a power of e
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I have used polyfit to convert a raw data file of current and voltage for a diode to an equation for current = f(voltage) and plotted the equation with a very good fit of a plot of the raw data. I would like to convert the polyfit exponents to a power of e or exp(power). I have looked at MATLAB help for taylor or maclaurin and other related functions with no corelation on my part. Is there something in the tool boxes that will do this conversion?
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Walter Roberson
on 18 Sep 2011
I am not clear as to what you are trying to do. Suppose the polynomial was (say) x^3 - x^2 + x + 1, then what output would you expect, or at least what form of output?
Are you trying to convert a polynomial to a single exponential that is itself in polynomial form? If so then you could do a series expansion of the ln() of the polynomial. That will, however, suffer from the usual problems of series expansion: increasing inaccuracy as you get further from the point of expansion. You would need to decide what your target range was and what your target error limit was over that range, in order to figure out how many terms you needed.
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