First, you have to do some sort of range reduction. Trig functions are periodic, so you need to reduce arguments down to a standard interval. For starters, you could reduce angles to be between 0 and 360 degrees. But by using a few identities, you realize you could get by with less. If you calculate … Read more
C/C++ provides sin(a), cos(a), tan(a), etc. functions that require a parameter with radian units rather than degrees. double DegreesToRadians(d) performs a conversion that is close but an approximate as the conversion results are rounded. Also machine M_PI is close, but not the same value as the the mathematical irrational π. OP’s code with 180 passed … Read more
First find the difference between the start point and the end point (here, this is more of a directed line segment, not a “line”, since lines extend infinitely and don’t start at a particular point). deltaY = P2_y – P1_y deltaX = P2_x – P1_x Then calculate the angle (which runs from the positive X … Read more
On some (especially older) platforms (see the comments below) you might need to #define _USE_MATH_DEFINES and then include the necessary header file: #include <math.h> and the value of pi can be accessed via: M_PI In my math.h (2014) it is defined as: # define M_PI 3.14159265358979323846 /* pi */ but check your math.h for more. … Read more
The parametric equation for a circle is x = cx + r * cos(a) y = cy + r * sin(a) Where r is the radius, cx,cy the origin, and a the angle. That’s pretty easy to adapt into any language with basic trig functions. Note that most languages will use radians for the angle … Read more
In GNU libm, the implementation of sin is system-dependent. Therefore you can find the implementation, for each platform, somewhere in the appropriate subdirectory of sysdeps. One directory includes an implementation in C, contributed by IBM. Since October 2011, this is the code that actually runs when you call sin() on a typical x86-64 Linux system. … Read more