fractional powers of negative numbers

[LV_Pro]

All righty then, got the formula node issue squared away, if you pardon the pun, but have run into another problem with it, essentially how to evaluate a fractional power of a negative number as in the following equation snippet:

(3.21004*(0.111667-B)**2.5)   where the subtraction results in a negative number? 

Thanks again,

[LV_Pro]

All right, if someone has an answer it would be cool to know, but for my application my customer just got back to me with the information that if the subtractions result in a negative number to be raised to the fractional power, then that term goes to zero. Kind of wish I had known that earlier, have other things to deal with in the program, particularly as I suspect that all these calculations will not truely be required in the long range, that the increased "accuracy" isn't required, but ...

Thanks!

[smercurio_fc]

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LV_Pro wrote:

All righty then, got the formula node issue squared away, if you pardon the pun,

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What issues with the formula node?

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essentially how to evaluate a fractional power of a negative number as in the following equation snippet:

(3.21004*(0.111667-B)**2.5)   where the subtraction results in a negative number?

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You could ask the same question by changing the 2.5 to 0.5. In this case it's a square root. So, you're trying to get the square root of a negative number. That brings you into the complex arena.

[johnsold]

Formula node: Different thread (right parenthesis).

x^2.5 = Sqrt(x^5).  For x < 0 this could be expressed as i*sqrt(abs(x)^5), where i = sqrt(-1).

Lynn