## How this is possible? "atan(x) function problem"

### Berat Can Karatas (view profile)

on 11 Oct 2019
Latest activity Answered by Hemant Verma

on 11 Oct 2019

### Hemant Verma (view profile)

Hello Everyone!
I want to calculate the arctan function in MatLab.
But the result is a situation that I do not understand.
Normally, x = atan (1/0) is compleately NaN
Also, matlab says that x = arctan (1/0)
= 1.5708
How is that possible?

R2019b

### Hemant Verma (view profile)

on 11 Oct 2019

Just recall the basics of trigonometry, for a right-angled triangle ,
where P denotes perpendicular, B denotes base and θ denotes angle between hypotenuse and base of triangle. In your case, where you want to compute arctan(1/0), the length of base B of triangle becomes 0. As B tends to 0, the hypotenuse and perpendicular of triangle start becoming colinear, and θ tends to 90 degrees or (i.e 1.5708) radians.
That's why you get ### Stephan (view profile)

on 11 Oct 2019
Edited by Stephan

### Stephan (view profile)

on 11 Oct 2019

What is the problem?
a = 1/0
a =
Inf
atan(a)
ans =
1.5708
fplot(@(x)atan(x),[-100 100],'-b','LineWidth',2)
looks like the Wiki-Entry for me: