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- Is there a way to calculate erfc(x) in JMP?

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Aug 8, 2012 8:59 AM
(3433 views)

Title is pretty self explanatory. I am trying to do non-linear least squares with a transcendental function that includes the error function (complement). However when I try to define a predict column using the function I was sad to find that there is no erf(x) in the transcendental group of functions. Without being able to calculate the error function there is no way that I can perform this nonlinear least squares in JMP! Does anyone know if it is possible to do in JMP? I can use an approximation using elementary functions, however I would like to avoid adding any error if at all necessary. Thanks!

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SurfaceThought

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Aug 8, 2012 9:29 AM
(5768 views)

erf(X) = 2 * Normal Distribution( :X * Root( 2, 2 ) ) - 1

erfc(X) = 1 - erf(X) = 2 * Normal Distribution(-:X * Root( 2, 2 ) )

where "Normal Distribution()" is the cumulative normal distribution function available in JMP for use in either scripts or column formulas.

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Aug 8, 2012 9:29 AM
(5769 views)

erf(X) = 2 * Normal Distribution( :X * Root( 2, 2 ) ) - 1

erfc(X) = 1 - erf(X) = 2 * Normal Distribution(-:X * Root( 2, 2 ) )

where "Normal Distribution()" is the cumulative normal distribution function available in JMP for use in either scripts or column formulas.

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Aug 8, 2012 1:25 PM
(3213 views)

Alright I think this is very much on the right track, thank you so much. I just have one question, whats the purpose of the colon inside the Normal Distribution function?

Edit: Yeah that's definitely what I needed. You rock! thanks for the help!

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Aug 8, 2012 1:30 PM
(3213 views)

The colon indicates that X is a column name. If you are defining a column formula in terms of other columns, this is how you would reference it.

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Aug 8, 2012 1:51 PM
(3213 views)

Oh okay great that's easy enough .

Thank You!