return any angle to (0 to 2pi) range

I have a cetain angle let us say x

and I want matlab to change x to become within 0 and 2pi range

example: if x=3pi

then the new value of x have to be pi

Answer 1

[James Tursa]

The short answer:

mod(x,2*pi)

The long answer for this particular mod operation, is that if you want to get the same answer for trig calculations for large inputs that MATLAB does, you need to do the mod differently:

atan2(sin(x),cos(x)); % effectively mod(x,2*pi)

E.g.,

>> x = 10
x =
    10
>> y = mod(x,2*pi)
y =
   3.716814692820414
>> sin(x)
ans =
  -0.544021110889370
>> sin(y)
ans =
  -0.544021110889370
>> x = 1e25
x =
     1.000000000000000e+25
>> y = mod(x,2*pi)
y =
     0
>> sin(x)
ans =
  -0.305257800135130
>> sin(y)
ans =
     0
>> z = atan2(sin(x),cos(x))
z =
  -0.310209139287907
>> sin(z)
ans =
  -0.305257800135130

Using the atan2( ) approach to doing the mod(x,2*pi) operation results in effectively the same angle that MATLAB uses for the trig operations.

[Osama Alkurdi]

how is the remain of the division of 2pi is what I was looking for?

can you explain it?

please!

[James Tursa]

I don't understand your question. The remainder of the division is the result of the mod operation.