Calculating tanh-1

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Mon, 12/08/2014 - 03:36 am

Hello,

does anyone know how we could calculate tanh-1 in IGOR? Is there any command for that?

I want to calculate the angle of a given tanh.

Thank you in advance
Thank you for the reply.

This gives me values from 2 to -2. I use wind direction values, thus values from 0 to 360, so this is not a reasonable result.

December 8, 2014 at 04:41 am - Permalink

I'm confused now.
Can you provide more explanation of what you need here please?

December 8, 2014 at 05:56 am - Permalink

Actually, I try to separate the wind direction into its two basic components. The nort-south and the east-west. Anyway, I want, if I know the tan(φ), to find the angle φ. Unfortunatelly, I can't take right results using atanh.

December 8, 2014 at 06:13 am - Permalink

I am sorry, I still don't understand.
Perhaps someone else can help?

December 8, 2014 at 06:31 am - Permalink

This gives me back values between -3 and 3, but this is not angle values again.

December 9, 2014 at 01:48 am - Permalink

steeve88 wrote:
This gives me back values between -3 and 3, but this is not angle values again.

That will be -pi to pi.
Try scaling the result by 180/pi.

December 9, 2014 at 02:04 am - Permalink

Make sure you read the documentation of the commands, e.g. execute the following from the command line:

DisplayHelpTopic "atan"
DisplayHelpTopic "atan2"

this says e.g. for atan2 that the input is expected to be in radians and the output values range from -pi to +pi.

December 9, 2014 at 02:05 am - Permalink

Thank you very much. That was the problem. Sometimes the solution is in front of our eyes but we can't see it.

I converted degrees to radians before the calculations, and finally I converted the result of arctan again into degrees.

December 9, 2014 at 04:06 am - Permalink