function to increase the range of inverse sine

The asin() function only returns values between (-pi/2, pi/2). How can I write a function to give me values between (0, 2pi)?

Answer 1

[Walter Roberson]

Please vote at http://www.mathworks.com/matlabcentral/answers/1325-what-is-missing-from-matlab#answer_12949 !

[Jan]

This will solve the problem by using the MATLAB 2013a or later. Not very efficient...

Answer 2

[the cyclist]

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).

Answer 3

[theodore panagos]

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