You have four options Finite Differences Automatic Derivatives Symbolic Differentiation Compute derivatives by hand. Finite differences require no external tools but are prone to numerical error and, if you’re in a multivariate situation, can take a while. Symbolic differentiation is ideal if your problem is simple enough. Symbolic methods are getting quite robust these days. … Read more
The standard method would be to do the separating axis test (do a google search on that). In short: Two objects don’t intersect if you can find a line that separates the two objects. e.g. the objects / all points of an object are on different sides of the line. The fun thing is, that … Read more
Here is the code, I don’t think there is any method in SE. It basically converts number to string and parses String and associates it with the weight for example 1000 1 is treated as thousand position and 1 gets mapped to “one” and thousand because of position This is the code from the website: … Read more
User @i_4_got points to this page with a very efficent solution in Python. I reproduce it here for convenience (since it would have made me happy to have it here): def ccw(A,B,C): return (C.y-A.y) * (B.x-A.x) > (B.y-A.y) * (C.x-A.x) # Return true if line segments AB and CD intersect def intersect(A,B,C,D): return ccw(A,C,D) != … Read more
Without converting to a string you could try Math.Floor(Math.Log10(n) + 1);
I’m the author of Java Matrix Benchmark (JMatBench) and I’ll give my thoughts on this discussion. There are significant difference between Java libraries and while there is no clear winner across the whole range of operations, there are a few clear leaders as can be seen in the latest performance results (October 2013). If you … Read more
eval is evil eval(“__import__(‘os’).remove(‘important file’)”) # arbitrary commands eval(“9**9**9**9**9**9**9**9”, {‘__builtins__’: None}) # CPU, memory Note: even if you use set __builtins__ to None it still might be possible to break out using introspection: eval(‘(1).__class__.__bases__[0].__subclasses__()’, {‘__builtins__’: None}) Evaluate arithmetic expression using ast import ast import operator as op # supported operators operators = {ast.Add: op.add, ast.Sub: … Read more
The fastest algorithm for general prime testing is AKS. The Wikipedia article describes it at lengths and links to the original paper. If you want to find big numbers, look into primes that have special forms like Mersenne primes. The algorithm I usually implement (easy to understand and code) is as follows (in Python): def … Read more
Compute unit vectors from the angles and take the angle of their average.
Try this code which makes use of a cross product: public bool isLeft(Point a, Point b, Point c){ return ((b.X – a.X)*(c.Y – a.Y) – (b.Y – a.Y)*(c.X – a.X)) > 0; } Where a = line point 1; b = line point 2; c = point to check against. If the formula is equal … Read more