Rewrite the function atan2f

Cherry65 · #1 21-Nov-2008, 09:32

Im doing some exercises from a book, and in one of them i have to rewrite the function atan2f. First, i wanted to explore a bit about this function, and while doing this i noticed that the results given by this function differed from the ones given in the book. For example, the book says that atan2f(4,2) = 63.46(degrees) and when i do this:

CPP / C++ / C Code:

#include <iostream>
#include <cmath>
using namespace std;

int main()
{
	cout << atan2f(4,2) << endl;
	system("PAUSE");
}

the result is 1.1 pi, that is 198 degrees. When i check this on a sheet of paper i realise that the result given by the book is the correct one. Whats wrong with this?

Maybe i misunderstood the excercise. This is the exercise:

Code:

Using atanf, write a function with the following prototype:

float MyArcTangent(float y, float x);

This function should examine the signs of coordinates of the point (x, y) and return the correct angle based on what quadrant the point lies in. Test your function with the following points: (2,4), (-1,5), (-6,-4), (4, -6). You sould get the following results:

MyArcTangent (4, 2) = 63.4671
MyArcTangent (5, -1) = 101.27
MyArcTangent (-4, -6) = 213.707
MyArcTangent (-6, 4) = -56.3385
Press any key to continue

Now that you have written the function yourself, you should know that the C++ standard math library already includes a function that does what your function does. Its prototype is:

float atan2f(float y, float x);

Blake · #2 21-Nov-2008, 11:51

The return value of 1.1 does not mean 1.1pi. It mean 1.1 radians. Multiply that by 180/pi to get degrees, and your answer will agree with the answer in the book.

Peter_APIIT · #3 24-Nov-2008, 21:28

How to code this function ? What this function does ?

Blake · #4 24-Nov-2008, 21:29

http://en.wikipedia.org/wiki/Atan2

Peter_APIIT · #5 25-Nov-2008, 02:32

Thanks for your help..

Thread Tools	Search this Thread
Show Printable Version Email this Page	Search this Thread: Advanced Search
Rate This Thread
Rate This Thread:

Similar Threads
Thread	Thread Starter	Forum	Replies	Last Post
run script command on ns2.26	newbie06	Computer Software Forum - Linux	65	19-Aug-2009 08:50
Airport Log program using 3D linked List : problem reading from file	batrsau	C Programming Language	11	29-Feb-2008 08:44
Flex and bison coding	lucky88star	C++ Forum	5	24-Dec-2007 12:57
Need Help with input files.	Efferus	C++ Forum	2	24-Nov-2007 17:19
[Include] Doubly-linked List	dsmith	C Programming Language	6	14-Apr-2006 14:12

Rewrite the function atan2f

Re: Rewrite the function atan2f

Re: Rewrite the function atan2f

Re: Rewrite the function atan2f

Re: Rewrite the function atan2f