math

count of distinct acyclic paths from A[a,b] to A[c,d]?

I'm writing a sokoban solver for fun and practice, it uses a simple algorithm (something like BFS with a bit of difference). now i want to estimate its running time ( O and omega). but need to know how to calculate count of acyclic paths from a vertex to another in a network. actually I want an expression that calculates count of valid ...

This is more a matlab/math brain teaser than a question

Here is the setup. No assumptions for the values I am using. n=2; % dimension of vectors x and (square) matrix P r=2; % number of x vectors and P matrices x1 = [3;5] x2 = [9;6] x = cat(2,x1,x2) P1 = [6,11;15,-1] P2 = [2,21;-2,3] P(:,1)=P1(:) P(:,2)=P2(:) modePr = [-.4;16] TransPr=[5.9,0.1;20.2,-4.8] pred_modePr = TransPr'*modePr MixPr...

Automatic camera calibration

From Wikipedia, camera resectioning is the process of finding the true parameters of the camera that produced a given photograph or video. Camera resectioning is also known as geometric camera calibration. Currently I am using Camera Calibration Toolbox for Matlab for my camera calibration. The toolbox returns calibration parameters suc...

Best fit curve for trend line

Problem Constraints Size of the data set, but not the data itself, is known. Data set grows by one data point at a time. Trend line is graphed one data point at a time (using a spline/Bezier curve). Graphs The collage below shows data sets with reasonably accurate trend lines: The graphs are: Upper-left. By hour, with ~24 data ...

How to get colliding effect or bouncy when ball hits the track.

** STILL NOT WORKING ** I am using below formula to move the ball circular, where accelX and accelY are the values from accelerometer, it is working fine. But the problem in this code is mRadius (I fixed its value to 50), i need to change mRadius according to accelerometer values and also i need bouncing effect...

Finding the string length of a integer in .NET

In .NET what is the best way to find the length of an integer in characters if it was represented as a string? e.g. 1 = 1 character 10 = 2 characters 99 = 2 characters 100 = 3 characters 1000 = 4 characters The obvious answer is to convert the int to a string and get its length but I want the best performance possible without the ove...

Looking for .NET Math method that will zero a negative integer

Similar in concept to Math.Abs() - I'm looking for a function that when given a positive integer will return the same integer. If given a negative, will return zero. So: f(3) = 3 f(0) = 0 f(-3) = 0 Yes, this is simple enough to write on my own but I'm wondering if the .NET Math class already has this built in or if the same can be a...

Getting a handle on GIS math, where do I start?

I am in charge of a program that is used to create a set of nodes and paths for consumption by an autonomous ground vehicle. The program keeps track of the locations of all items in its map by indicating the item's position as being x meters north and y meters east of an origin point of 0,0. In the real world, the vehicle knows the loc...

What is the name of this geometrical function?

In a two dimentional integer space, you have two points, A and B. This function returns an enumeration of the points in the quadrilateral subset bounded by A and B. A = {1,1} B = {2,3} Fn(A,B) = {{1,1},{1,2},{1,3},{2,1},{2,2},{2,3}} I can implement it in a few lines of LINQ. private void UnknownFunction(Point to, Point from, List<Poi...

Maths Question: number of different permutations

This is more of a maths question than programming but I figure a lot of people here are pretty good at maths! :) My question is: Given a 9 x 9 grid (81 cells) that must contain the numbers 1 to 9 each exactly 9 times, how many different grids can be produced. The order of the numbers doesn't matter, for example the first row could conta...

How can I handle weird errors from calculating acos / sin / atan2?

Has anyone seen this weird value while handling sin / cos/ tan / acos.. math stuff? ===THE WEIRD VALUE=== -1.#IND00 ===================== void inverse_pos(double x, double y, double& theta_one, double& theta_two) { // Assume that L1 = 350 and L2 = 250 double B = sqrt(x*x + y*y); double angle_beta = atan2(y, x); dou...

how to calculate a bill from several tables on mysql?

I'm using mysql to create an hotel booking system, but i am struggling a little bit to calculate the final bill. I need a SELECT command to get data from several tables and make some calculations. Basically I just need to get the 'night cost' from a table called 'room_types'. Then, use DATEDIFF function to get the difference of days be...

Make character escape from shot

Hello all math masters, I got a problem for you: I have a 2D game (top down), and I would like to make the character escape from a shot, but not just walk away from the shot (I mean, don't be pushed by the shot), I want it to have a good dodging skills. The variables are: shotX - shot x position shotY - shot y position shotSpeedX - s...

[MATH]Project an axis to a plane

how do i project the X axis to a plane if the plane is defined by three points? see pic here: http://129.25.16.135:2080/v6.5/books/usb/graphics/iconventions-local-surfaces.png The default local 1-direction is the projection of the global x-axis onto the surface. If the global x-axis is within 0.1° of being normal to the surface, the loc...

Graph theory in python

I was wondering how people deal with graph theory in python? How is a graph stored? Are there libraries for this? For example how would I input a graph and then find its Chromatic polynomial? Or its girth? Or the number of unique spanning trees? How about problems that involve edge weight like salesman problems? I don't need all of the...

Finding an element in a cyclic group of prime order

Greetings! How do I check if an element a belongs to a specific cyclic group G of prime order, given the generator? Right now i simply generate all the elements in the group, save them into a container and check if the element is in it. This is the code im currently using to generate all the elements of the group: public HashSet<BigInt...

Draw arrow on line

Hi, I have this code: CGPoint arrowMiddle = CGPointMake((arrowOne.x + arrowTo.x)/2, (arrowOne.y + arrowTo.y)/2); CGPoint arrowLeft = CGPointMake(arrowMiddle.x-40, arrowMiddle.y); CGPoint arrowRight = CGPointMake(arrowMiddle.x, arrowMiddle.y + 40); [arrowPath addLineToScreenPoint:arrowLeft]; [arrowPath addLineToScreenPoint:arrowMiddle...

How to calculate the curve of a linear floating point number in Javascript?

How do I calculate a curve of a linear floating point number (0 to 1) and get another floating point number as a result? What I want is up until the half (0..0.5), to be inversed logarithmic and high than that to be logarithmic like a curve according to the given linear value. ...

Which euler rotations can I use ?

I have two Cartesian coordinates. There are xyz and BIG XYZ. I want to make these are parallel to each other. For example, x paralel to X ,y parallel to Y and z paralel to Z. I use a rotation matrix but I have a lot of different rotation matrices. For example I have 3D point in xyz Cartesian coordinates and it's called A and I want ...

Question about numbers

it's a task, on which i think during whole day. i have four integer numbers a, b, c, d, and integer x[1,40]. i must write a program, which can find the values of {a,b,c,d}, for which one of following equations is true for any 1<=x<=40 x=a or x=b or x=a+b or x=a+b+c+d or x+a=c+d or x+a+b=c+d or ... x+...