please help with this function

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francis
francis 2013-7-23
function [th rad]=cartopolar25(x,y
t=atan(y/x); rad=sqrt(x^2+y^2); if if x<0 if y<0 th=180+t return else th=180-t return end else if y<0 th=-t return else th=t return end end
end end
Hi I need help with this code, if you guys see any mistakes please let me know. I have to make a function to determine the polar coordinates from the Cartesian plane, thanks for the help yes I was able to get the degrees now all I need is the radians any tips with this current format thanks

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采纳的回答

Narges M
Narges M 2013-7-23
your function is this:
function [th rad]=cartopolar25(x,y)
th = atan(y/x);
rad = sqrt(x^2+y^2);
if x<0
if y<0
th=th+180;
else
th=th-180;
end
else
if y<0
th=-th;
end
end
and you need to call it like this:
[t,r] = cartopolar25(-11,20);
the output will be:
t =
-181.0680
r =
22.8254

更多回答（3 个）

Jonathan Sullivan
Jonathan Sullivan 2013-7-23
help atan2
doc atan2
Gorji
Gorji 2013-7-23
What is Y and X? Are they matrix? I think the structure of 'if' is incorrect you must use if & elseif & else
  2 个评论
francis
francis 2013-7-23
Y and X are supposed to be the coordinates, if I used that function with the points (-11,20) it should be able to give me radians=2.8 and deg=-118.8, I can do all of that on paper but here I am just trying to figure out I dont know how to defined Y and X, I try by using a vector and still gives me the same error "Undefined function or variable "y".
francis
francis 2013-7-23
I was able to get the degrees with a few changes yess, all I need some tips of putting the radiants on to this format, thanks

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Andrew Reibold
Andrew Reibold 2013-7-23
atan doesn't take the 'y over x' value you seem to be thinking of. It takes an angle in radians....
Y = atan(X) returns the inverse tangent (arctangent) for each element of X. For real elements of X, atan(X) is in the range [–π/2, π/2].
The atan function operates element-wise on arrays. The function's domains and ranges include complex values. All angles are in radians.
Example Graph the inverse tangent function over the domain –20 ≤ x ≤ 20. x = -20:0.01:20; plot(x,atan(x)), grid on

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