math

What's the right way to utilize ARM SIMD on iPhone for Game vector/matrix operation?

I'm making an vector/matrix library for Game which utilizes SIMD unit on iPhone (3GS or later). How can I do this? I searched about this, now I know several options: Accelerate framework (BLAS+LAPACK+...) from Apple (iPhone OS 4) OpenMAX implementation library from ARM GCC auto-vectorization feature What's the most suitable way for v...

Draw fitted line (OpenCV)

I'm using OpenCV to fit a line from a set of points using cvFitLine() cvFitLine() returns a normalized vector that is co-linear to the line and a point on the line. See details here Using this information how can I get the equation of a line so that I can draw the line? ...

How to get visible size of DisplayObject with perspective projection

The following is entirely a math question. As we know, PerspectiveProjection delivers perspective transformations in 3D represented by the interdependent values of fieldOfView and focalLength according to the following formula: focalLength = stageWidth/2 * (cos(fieldOfView/2) / sin(fieldOfView/2) Q: How to get the visible on-scree...

Delphi Math: Why is 0.7<0.70?

If I have variables a, b, an c of type double, let c:=a/b, and give a and b values of 7 and 10, then c's value of 0.7 registers as being LESS THAN 0.70. On the other hand, if the variables are all type extended, then c's value of 0.7 does not register as being less than 0.70. This seems strange. What information am I missing? ...

Affine transformation algorithm.

Does anyone know of any standard algorithms to determine an affine transformation matrix based upon a set of known points in two co-ordinate systems? ...

How to determine Scale of Line Graph based on Pixels/Height?

I have a problem due to my terrible math abilities, that I cannot figure out how to scale a graph based on the maximum and minimum values so that the whole graph will fit onto the graph-area (400x420) without parts of it being off the screen (based on a given equation by user). Let's say I have this code, and it automatically draws squa...

Discrepancy between the values computed by Fortran and C++

I would have dared say that the numeric values computed by Fortran and C++ would be way more similar. However, from what I am experiencing, it turns out that the calculated numbers start to diverge after too few decimal digits. I have come across this problem during the process of porting some legacy code from the former language to the ...

XNA Track rotated pixel positions

Hi, Im making a game in xna where a tank has to move over a landscape. I need to be able find the bottom of the tank when it is rotated so I can make it move up and down as the player goes over the landscape. for example if i have a sprite at with its top left corner at 400,300 and i rotate it around its center by 45 degrees around its...

what math do i need to convert this number

given an X, what math is needed to find its Y, using this table? x->y 0->1 1->0 2->6 3->5 4->4 5->3 6->2 language agnostic problem and no, i dont/cant just store the array, and do the lookup. yes, the input will always be the finite set of 0 to 6. it wont be scaling later. ...

Silverlight 3 ArcSegment to always draw circle's

Hi everyone, Ok, my arcSegment must always draw Circle's. For this reason I calculate the Arc's Width with the following formula: arcXRadius = (4 * Math.Pow(height, 2) + Math.Pow(distanceArcPoints, 2)) / (8 * height); so Arcs.Size = (arcXRadius,height) But seems that the height is scaled down when drawn. I want to add a small Circle ...

How would I find all sets of N single-digit, non-repeating numbers that add up to a given sum in PHP?

Let's say I want to find all sets of 5 single-digit, non-repeating numbers that add up to 30... I'd end up with [9,8,7,5,1], [9,8,7,4,2], [9,8,6,4,3], [9,8,6,5,2], [9,7,6,5,3], and [8,7,6,5,4]. Each of those sets contains 5 non-repeating digits that add up to 30, the given sum. Any help would be greatly appreciated. Even just a starting...

How do i break a number down into a percentage (0 - 100%)? Details inside...

I am using a JS progress bar that is set using a percentage: 0 to 100 (percent). I need the progress bar to reach 100% when 160,000 people have signed a certain form. I have the total number of signers set in a PHP variable but am lost on how to do the math to convert that into a percentage that fits within 1 - 100 (so that the progress ...

How can I calculate a trend line in PHP?

So I've read the two related questions for calculating a trend line for a graph, but I'm still lost. I have an array of xy coordinates, and I want to come up with another array of xy coordinates (can be fewer coordinates) that represent a logarithmic trend line using PHP. I'm passing these arrays to javascript to plot graphs on the...

create a random sequence, skip to any part of the sequence

Hi everyone, In Linux. There is an srand() function, where you supply a seed and it will guarantee the same sequence of pseudorandom numbers in subsequent calls to the random() function afterwards. Lets say, I want to store this pseudo random sequence by remembering this seed value. Furthermore, let's say I want the 100 thousandth n...

Project Euler 9 Understanding

This question states: A Pythagorean triplet is a set of three natural numbers, a b c, for which, a2 + b2 = c2 For example, 32 + 42 = 9 + 16 = 25 = 52. There exists exactly one Pythagorean triplet for which a + b + c = 1000. Find the product abc. I'm not sure what's it trying to ask you. Are we trying to find a2 + b...

Plotting Bessel function in MATLAB

In MATLAB how do you plot f(r) = { 2*J1(a*r) / r }^2 where a = 2*pi and J1 is Bessel function of the 1st kind and r = sqrt(x^2 + y^2) This should plot in 3D, i.e. kind of be like a bubble (not sure how to do this) ...

Round an integer to the nearest int that is lower than or equal to it and a multiple of 64

Given an integer x, how would you return an integer y that is lower than or equal to x and a multiple of 64? ...

How to create a magic square in PHP?

I'd like to try my hand at creating a Magic Square in PHP (i.e. a grid of numbers that all add up to the same value), but I really don't know where to start. I know of the many methods that create magic square, such as starting "1" at a fixed position, then moving in a specific direction with each iteration. But that doesn't create a tru...

Can't get my object to point at the mouse.

I'm using a combination of SDL and OpenGL in a sort of crash course project to teach myself how this all works. I'm really only interested in OpenGL as a way to use acceleration in 2D games so I just need this to work in a 2D plane. I have been having a lot of problems today with my current issue, I would like an object to point toward...

How do I determine when two moving points become visible to each other?

Suppose I have two points, Point1 and Point2. At any given time, these points may be at different positions-- they are not necessarily static. Point1 is located at some position at time t, and its position is defined by the continuous functions x1(t) and y1(t) giving the x and y coordinates at time t. These functions are not differenti...