# function to increase the range of inverse sine

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rick on 14 Sep 2011
Edited: Walter Roberson on 26 Oct 2018
The asin() function only returns values between (-pi/2, pi/2). How can I write a function to give me values between (0, 2pi)?

Walter Roberson on 14 Sep 2011
Jan on 14 Sep 2011
This will solve the problem by using the MATLAB 2013a or later. Not very efficient...

the cyclist on 14 Sep 2011
You can force the output to be within the range (0,2pi) by applying the mod() function:
>> mod(asin(x),2*pi)
Given only one input argument, you can't infer precisely which quadrant to return. Walter's answer points to a list of requested features (specifically, more two-argument versions of inverse trig functions).

theodore panagos on 26 Oct 2018
Edited: Walter Roberson on 26 Oct 2018
You can have the asin(x,y) from 0 to 2*pi by the formula:
asin(x,y)=pi-pi/2*(1+sgn(x))*(1-sgn(y^2))-pi/4*(2+sgn(x))*sgn(y) -sgn(x*y)*asin((abs(x)-abs(y))/sqrt(2*x^2+2*y^2))
there is x=x2-x1 and y=y2-y1

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