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

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?

Sorry about this simple question but I could not find any information on the network.

Answer 1

[Hemant Verma]

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

Answer 2

[Stephan]

What is the problem?

https://en.wikipedia.org/wiki/Inverse_trigonometric_functions#arctan

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:

https://en.wikipedia.org/wiki/Inverse_trigonometric_functions#/media/File:Arctangent_Arccotangent.svg