MPFXEMGPeak
MPFXEMGPeak (cw, yw, xw)
The MPFXEMGPeak function implements a single exponentially modified Gaussian peak with no Y offset in the format of an all-at-once fitting function. The exponentially modified Gaussian peak shape is a convolution of an exponential and a Gaussian peak.
Parameters
| cw | Coefficient wave, which must be a double-precision wave. | ||||||||
| The Gaussian peak shape is defined by the coefficients as follows: | |||||||||
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| cw must be a double precision wave. | |||||||||
| yw | Y wave into which values are stored. | ||||||||
| yw may be either double precision or single precision. | |||||||||
| xw | X wave containing the X values at which the peak function is to be evaluated. | ||||||||
| xw may be either double precision or single precision. | |||||||||
Details
There is no analytic expression for peak parameters of common interest like the amplitude, location and width. The Multipeak Fitting package uses numerical techniques to get approximations.
This function is primarily intended to support the Multipeak Fitting package.
To use MPFXEMGPeak as a fitting function, wrap it in an all-at-once user-defined fitting function:
Function FitVoigtPeak(Wave cw, Wave yw, Wave xw) : FitFunc
Variable dummy = MPFXEMGPeak(cw, yw, xw)
End
The assignment to "dummy" is required because you must explicitly do something with the return value of a built-in function.
The implementation of this function involves the erfcx function.
If the waves do not satisfy the number type requirements, the function returns NaN. A successful invocation returns zero.