# [ncl-talk] Asymmetric Sigmoidal function Error

Dennis Shea shea at ucar.edu
Wed Mar 20 08:04:27 MDT 2019

```I have never seen any quantity raised to the 186038500 power.  :-)
Double precision.

d = 2510.02d
a = 27.02d
b = 4.53d
c = 587.02d
m = 186038500
x = fspan(1d,25d,25)
y = d+(a-d)/(1+(x/c)^b)^m

print(x+"   "+y)

(0)    1   27.15261929070493
(1)    2   30.08187239595736
(2)    3   46.1741014424274
(3)    4   96.80117019817772
(4)    5   214.0957520905181
(5)    6   433.778538060867
(6)    7   777.1109061695299
(7)    8   1224.84337331945
(8)    9   1702.177160490996
(9)    10   2103.542510714167
(10)    11   2357.030426786869
(11)    12   2470.21751524107
(12)    13   2503.483073444604
(13)    14   2509.408653665199
(14)    15   2509.991006732112
(15)    16   2510.019387317239
(16)    17   2510.019995000746
(17)    18   2510.019999986545
(18)    19   2510.01999999999
(19)    20   2510.02
(20)    21   2510.02
(21)    22   2510.02
(22)    23   2510.02
(23)    24   2510.02
(24)    25   2510.02

On Wed, Mar 20, 2019 at 1:24 AM ABDULLA SAKALLI <abdulla.sakalli at iste.edu.tr>
wrote:

> Dear All,
> I’m trying to calculate the wind production of a wind farm. According to
> the data sheet of the wind turbine, I should use a 5th grades asymmetric
> sigmoidal function which is:
>
> f(x)=d+(a-d)/(1+(x/c)^b)^m
>
> d=2510.02
> a=27.02
> b=4.53
> c=587.02
> m=186038500
>
> where x is the wind speed (3 m/s — 25 m/s).
>
> When I run the code, the results are 27.02 which is equal to parameter “a”.
>
> I cannot see any error during the script’s run. Does anyone has an idea or
> suggestion how I can fix it?
>
> Thank you very much in advance.
>
> Kind regards,
>
>
> ---------------------------------------------------------------------------
> Assoc. Prof. Abdulla Sakalli
>
> Iskenderun Technical University
> Faculty of Engineering and Natural Sciences
> Dept. Industrial Engineering
> Merkez Kampus
> Iskenderun-Hatay-Turkey
> as at abdulla-sakalli.com
> abdulla.sakalli at iste.edu.tr
> +90 326 613 5600
> +90 536 506 9191
>
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