You don’t want to convert to degrees, because you already have your number (90) in degrees. You need to convert 90 from degrees to radians, and you need to do it before you take the sine: >>> np.sin(np.deg2rad(90)) 1.0 (You can use either deg2rad or radians.)
Here’s the guaranteed fastest possible sine function in C++: double FastSin(double x) { return 0; } Oh, you wanted better accuracy than |1.0|? Well, here is a sine function that is similarly fast: double FastSin(double x) { return x; } This answer actually does not suck, when x is close to zero. For small x, … Read more
Instead of calculating sine as a function of time, maintain a sine/cosine pair and advance it through complex number multiplication. This doesn’t require any trigonometric functions or lookup tables; only four multiplies and an occasional re-normalization: static const double a = 2 * M_PI * 280 * 30e-6; static const double dx = cos(a); static … Read more
Given a radius length r and an angle t in radians and a circle’s center (h,k), you can calculate the coordinates of a point on the circumference as follows (this is pseudo-code, you’ll have to adapt it to your language): float x = r*cos(t) + h; float y = r*sin(t) + k;
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
radians = degrees * (pi/180) degrees = radians * (180/pi) As for implementation, the main question is how precise you want to be about the value of pi. There is some related discussion here
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
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
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
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