how to write ( a=(arctan(b/c)pir)/90) in Matlab 2014

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harshal j 2015-12-10

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评论： harshal j 2015-12-15

Hi i want to write (arctan(b/c)*pi*r)/90)this formula in matlab 2014, I don't know how to write 'arctan' in matlab 2014. plase help, thanks in advance

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Walter Roberson 2015-12-10

Are you sure that it is multiply by pi and divide by 90, and not multiply by 90 and divide by pi?

Are you trying to get an answer in degrees or in radians or in some other units? The MATLAB arctan functions return radians, but that formula looks like it is trying to find the radians of 1/2 of an angle expressed in degrees.

harshal j 2015-12-10

Thanks for the comments, yes the formula is correct and it is multiply by pi and divide by 90. I am trying to find the values in degree. Please help if possible

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Answer 1

Torsten 2015-12-10

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编辑：Torsten 2015-12-10

http://de.mathworks.com/help/matlab/ref/atan.html

http://de.mathworks.com/help/matlab/ref/atan2.html

Best wishes

Torsten.

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Answer 2

Walter Roberson 2015-12-10

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在 MATLAB Online 中打开

If you want the arctan of b/c and you want it expressed in degrees, then use atand()

atand(b/c)

The result will be in the range -90 to +90. atand() cannot be used for the full 4-quadrant arctan

The normal arctan functions are atan() and atan2(), both of which return radians. atan(b/c) returns [-pi/2, pi/2] radians and atan2(b,c) returns [-pi, pi] radians.

The conversion from radians to degrees is to multiply by 180 and divide by pi. Applying that to the [-pi, pi] range would be +/- pi*(180/pi) which would be +/- 180 as you would hope for a 4-quadrant arctan. The formula you were using would be for +/- pi*(pi/90) which would be +/- pi^2/90 which would be about +/- 0.1097

It is not clear why you would multiply an angle by r, especially if r represents a radius??

Please re-check your formula as it seems likely to be wrong.