Azzera filtri
Azzera filtri

Changing the atan function so that it ranges from 0 to 2*pi

299 visualizzazioni (ultimi 30 giorni)
I know that the matlab atan function returns values in the range of -pi/2 to pi/2. How do i change it so that it goes over the full range 0 to 2*pi?
My first attempt was using a while loop, but it was incorrect.
I need to write a function mfile to set the built-in matlab function atan in the range of 0 to 2*pi without using atan2. im new to matlab so im unsure of what to do.
Thank you
  2 Commenti
wenjun kou
wenjun kou il 8 Mar 2017
Modificato: wenjun kou il 8 Mar 2017
Although you don't want to use atan2, I thought I might just put this out there since atan2 returns a range between -pi to pi:
a = atan2(y, x);
a = a .* (a >= 0) + (a + 2 * pi) .* (a < 0);

Accedi per commentare.

Risposta accettata

Daniel Svedbrand
Daniel Svedbrand il 14 Set 2018
Modificato: John D'Errico il 3 Ago 2023
Adding mod 2*pi to atan2 should work just fine
z = mod(atan2(y,x),2*pi);
  6 Commenti
Feruza Amirkulova
Feruza Amirkulova il 3 Ago 2023
Yes, mod(atan2(y,x),2*pi) worked and its gradients are the same as for (atan2(y,x)).

Accedi per commentare.

Più risposte (4)

Walter Roberson
Walter Roberson il 12 Giu 2011
Use atan2() instead.
  5 Commenti
Paulo Silva
Paulo Silva il 12 Giu 2011
I didn't include that statement on purpose, when none of the others if statements are true the value of v is NaN, you could also do this:
if isnan(v)
error('Arguments must be different from zero')
end
KA
KA il 12 Giu 2011
ok, did not know that, thanks again

Accedi per commentare.


Paulo Silva
Paulo Silva il 12 Giu 2011
The Wikipedia got all explained, you just need to do the code, it's very simple.
function v=myatan(y,x)
if nargin==1 %just in case the user only gives the value of y myatan(y)
x=1;
end
v=nan;
if x>0
v=atan(y/x);
end
if y>=0 & x<0
v=pi+atan(y/x);
end
if y<0 & x<0
v=-pi+atan(y/x);
end
if y>0 & x==0
v=pi/2;
end
if y<0 & x==0
v=-pi/2;
end
if v<0
v=v+2*pi;
end
end
  2 Commenti
Mehmet Can Türk
Mehmet Can Türk il 9 Apr 2022
Modificato: Mehmet Can Türk il 9 Apr 2022
I checked the Wikipedia link and tested the code. First of all, thank you so much for the contribution.
I wanted to convert atan2 function from Matlab into another environment which supports only atan function. So I deleted the if block and everything worked perfectly.

Accedi per commentare.


Kent Leung
Kent Leung il 21 Mar 2018
Modificato: Kent Leung il 21 Mar 2018
Better late than never. (Also posting as a future reference to myself.) The function below accepts y & x as vectors in Matlab. Rather than using 'if' statements, the below might be faster if there is some parallelization implemented in the built-in index searching.
Note: I have a slight disagreement with the above for the x>0 & y<0 case, as well as the for x=0 & y<0 case. The code below gives 0 to 2pi.
function v=myatan(y,x)
%---returns an angle in radians between 0 and 2*pi for atan
v=zeros(size(x));
v(x>0 & y>=0) = atan( y(x>0 & y>=0) ./ x(x>0 & y>=0) );
v(x>0 & y<0) = 2*pi+atan( y(x>0 & y<0) ./ x(x>0 & y<0) );
v(x<0 & y>=0) = pi+atan( y(x<0 & y>=0) ./ x(x<0 & y>=0) );
v(x<0 & y<0) = pi+atan( y(x<0 & y<0) ./ x(x<0 & y<0) );
v(x==0 & y>=0) = pi/2;
v(x==0 & y<0) = 3/2*pi;
end

theodore panagos
theodore panagos il 27 Ott 2018
You can use the formula:
atan(x,y)=pi-pi/2*(1+sgn(x))*(1-sgn(y^2))-pi/4*(2+sgn(x))*sgn(y) -sgn(x*y)*atan((abs(x)-abs(y))/(abs(x)+abs(y)))
x=x2-x1 and y=y2-y1
  1 Commento
theodore panagos
theodore panagos il 6 Ago 2023
atan2(x,y)=pi/2*(1-sign(x))*(1-sgn(y^2))+pi()/4*(2-sgn(x))*sign(y)-sign(x*y)*atan((abs(x)-abs(y))/(abs(x)+abs(y)))

Accedi per commentare.

Categorie

Scopri di più su Get Started with MATLAB in Help Center e File Exchange

Prodotti

Community Treasure Hunt

Find the treasures in MATLAB Central and discover how the community can help you!

Start Hunting!

Translated by