How to convert radians to degrees?

Hi, I have this code,

clear all, close all, clc, 
r = 0.08;
t = 2;

for n = 1:180,
  M(1,n) = r*cos(t);  %x length from center
  M(2,n) = r*sin(t);  %y length from center
  t = t+2;
end

It is meant to find the x,y distance from the center of a circle with fixed radius (Basically calculating x,y coordinates of circumference).

However the coordinates are coming wrong and it is because Matlab is performing calculations in radians rather than in degrees. (I cross checked the values with calculator) And I don't know how to convert to radians, and none of the forum results made sense to me.

Thanks, Rohan

Answer 1

[José-Luis]

There is a built in function for that:

 doc deg2rad

But it is rather trivial to implement it yourself:

 myTrans = @(x) x./360.*(2.*pi());
 myTrans(180)

 ans =

    3.1416

[James Tursa]

To avoid two scalar * vector multiplies, group the constant scalars:

x * (180/pi()); % rad --> deg
x * (pi()/180); % deg --> rad

[José-Luis]

Thanks. I was just trying to make the formula explicit though.

[Rohan Repale]

I figured out, i had to use 'sind' and 'cosd'. Thank you all for your replying.

[James Tursa]

No, you did not have to use sind and cosd. They work, but the many other suggestions on this thread using sin and cos correctly also work.

[Rohan Repale]

@James, mathematically speaking the other suggestions must work as well, but the output was not matching my expected output. But when I used sind and cosd, it worked perfect. Maybe I was not doing it right. Anyways thanks for the help

[Ivan-V-Timofeev]

deg2rad

It does not work without toolbox > geo > private > deg2rad.m http://mooring.ucsd.edu/software/matlab/doc/toolbox/geo/private/deg2rad.html

Answer 2

[Iain]

Degrees = 180 * radians / pi.

Rearrange as needed ;)

[James Tursa]

To avoid two scalar * vector multiplies, group the constant scalars:

Degrees = radians * (180 / pi);

[Rohan Repale]

I know the formula, Its not working right. IS there any code to convert the units (radtodeg doesn't seem to be working) ? Or can the units be set through settings/preferences?

[Iain]

Put the conversion in the right place(s)?

[Rohan Repale]

hi James, I just tried it. It doesnt seem to work either.

[Iain]

Radians = degrees * (pi/180)

"t" is in degrees, and you want it in radians when put into cos and sin.

cos(t * (pi/180)) and sin(t * (pi/180)) is the conversion rearranged as needed, AND put in the right place...

[José-Luis]

Doesn't seem to work... How? Please show what you mean.

Answer 3

[per isakson]

Wiki knows http://en.wikipedia.org/wiki/Radian