Indeed, it is a very low number, awfully close to zero. Here’s a great article which can help you understand the common challenges and pitfalls of floats: “What Every Computer Scientist Should Know About Floating-Point Arithmetic“
>>> import math >>> print math.sin.__doc__ sin(x) Return the sine of x (measured in radians). math.sin expects its argument to be in radians, not degrees, so: >>> import math >>> print math.sin(math.radians(68)) 0.927183854567
The number π cannot be represented exactly as a floating-point number. So, np.radians(180) doesn’t give you π, it gives you 3.1415926535897931. And sin(3.1415926535897931) is in fact something like 1.22e-16. So, how do you deal with this? You have to work out, or at least guess at, appropriate absolute and/or relative error bounds, and then instead … 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
I know I will never get a 100% precise value of these numbers, but AT LEAST I was expecting to get the same “unprecise” value of sin and cos of complementary angles. Why? The are calculated differently, so different floating point errors will occur (and accumulate). What you see is not an error; FP arithmetic … Read more
The answer is only 0 for sin(pi) – did you include all the digits of Pi ? -Has anyone else noticed a distinct lack of, irony/sense of humour around here?
The problem is int center = radius which you are setting int radius = 576. This doesn’t make sense as surely you are rotating about a point that should have an x and y location. Given you are rotating around the origin the center x and y should both be 0 not 576. So, given … Read more
It seems you are measuring distance (R) in meters, and bearing (theta) counterclockwise from due east. And for your purposes (hundereds of meters), plane geometry should be accurate enough. In that case, dx = R*cos(theta) ; theta measured counterclockwise from due east dy = R*sin(theta) ; dx, dy same units as R If theta is … 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;
As Julia points out Sujit Pal’s example is very useful but the Lucene 4 API has substantial changes. Here is a version rewritten for Lucene 4. import java.io.IOException; import java.util.*; import org.apache.commons.math3.linear.*; import org.apache.lucene.analysis.Analyzer; import org.apache.lucene.analysis.core.SimpleAnalyzer; import org.apache.lucene.document.*; import org.apache.lucene.document.Field.Store; import org.apache.lucene.index.*; import org.apache.lucene.store.*; import org.apache.lucene.util.*; public class CosineDocumentSimilarity { public static final String CONTENT … Read more