Example

> atan(0)
        0
> atan(1)
    0.785
> pi/2
     1.57
> atan(-inf())
    -1.57
> atan(inf())
     1.57
> atan(1+1j)
     1.02 + 0.402i
> Mat= (rand(2,3)+rand(2,3)*(0+1j))*5
 Mat =
 matrix columns 1 thru 3
               5 + 3.32i            3.24 + 1.02i           0.185 + 3.27i
           4.87 + 0.423i           1.67 + 0.837i          0.809 + 0.644i

> atan(Mat)
 matrix columns 1 thru 3
          1.43 + 0.0907i          1.29 + 0.0822i           1.55 + 0.314i
           1.37 + 0.017i            1.1 + 0.197i          0.807 + 0.365i