# Questions tagged [math]

Programming questions that are significantly affected or best defined by the underlying mathematics of the problem.

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96 views

### How to show fluctuating data smoothly and accurately?

I am working on a project in which I have to read data from liquid level sensor installed in tank which measures fluid level and sends output in millivolt. The device has predefined ranges of voltage ...
52 views

### Should absolute value functions be overloaded to give the norm of vector-like data structures?

The absolute value function is an instance of the norm function in one dimension. I've seen instances of libraries where the absolute value function is overloaded to also take the norm of higher ...
63 views

### What is the difference between BigInt and “Computer Algebra System” integers?

Obviously I imagine a CAS does more than BigInt does. But I'm wondering if there is a difference in implementation between BigInt integers and CAS integers (whatever they may be, symbols?). Wondering ...
129 views

### How to minimize size of data given the need for a null pointer?

So I don't know how to formulate this clearly, as it's quite confusing. Hence the reason for asking this question, to overcome the confusion. I will do my best to make it clear, but part of the ...
52 views

### Suitable way to round results returned by any function of a class

Assume there is a class Shape. The class has two functions area() and perimeter(). Let's say Circle and Square inherit from Shape and override these methods. Obviously the results are going to be ...
43 views

### Resolving Dependencies and Incompatibilities Deterministically

Problem Description I'm working in Python and I've been having a problem designing something to handle the following (abstracted) system: I have some objects (lets call them Nodes) that can be in ...
119 views

### Is there a way to specify a two-way relationship between variables?

Let's say we have two variables, eta and phi related by eta = cos(phi). Is there a way to link these variables in any programming language such that there's no need for two different functions, ...
173 views

### Loan Amortization Schedule - Precision and rounding

I have been playing around making amortization schedules in PHP. My php.ini currently has the precision set to 14. I understand going into this that there will be rounding errors however I am hoping ...
5k views

### Why is the norm of a complex number in the C++ complex library actually the square of the norm?

In the C++ complex library, the method norm() of a complex number actually returns the square of what I have learned is usually called the "Norm". Reference: std::norm For example, std::norm() of (3,...
320 views

### Smallest Rubik's cube state representation

I'm trying to determine what is the fewest number of bits I need to represent the state of a Rubik's cube. (EDIT: I am assuming the cube is a valid Rubik's cube that has not been altered and only ...
138 views

### How to do grid systems with floats given precision causes problems

I've been trying to create a grid system that can use any grid size and start at any given anchor point rather than always at 0,0. The problem however is imprecision makes it impossible, even the ...
136 views

### How can I calculate the radius of an arc given by a series of points

Given a series of points, I need to assert that the plotted points form an arc (with a certain level of confidence), and I need to approximate the radius of the arc. For example, the following points ...
91 views

### Seeking appropriate design pattern(s) to describe most function-based mathematical problems

I have been looking for a good, general design pattern to implement simple mathematical structures where functions have the following properties: know which parameters they contain, parameters are "...
182 views

### Big-O Notation and Calculus [closed]

I was wondering if there are any calculus relationships implicit in Big-O notation. For example, an algorithm linear according to Big-O notation reduces the size of the problem by a constant amount ...
126 views

### Generic way to describe data synchronization between systems?

Is there a generic way (useful formalisms) to think about data synchronization between two systems, especially in the case of slightly asymmetric roles (eg, one system contain master data, another one ...
182 views

### What effects does memory space have on bitwise shifts?

It is true that the bitwise left shift operation (shl) doubles the value of the integer being shifted. However, when constrained to a finite space, such as 8 bits for example, left shift will begin to ...
247 views

### Gerstner Wave equation from tessendorf paper, mesh penetrates itself

I have been learning to create water waves in a mesh from a paper commonly known as the Tessendorf paper. Which is quite well known. But those who don't know this is the equations it mentions in the ...
63 views

### Best way to encode a queryable number to another unique queryable number? (database outsourcing)

So lets say you want to outsource your database to a third party and be able to query on it on their server but you want to "encode" the salary column of the users on their server, aka hide the real ...
155 views

### Find two horizontal lines to minimize distance to scattered points

I am having trouble with a coding question that I found practicing for a interview: A scatter graph of points on a page, draw two horizontal lines (these lines are parallel) across the page such that ...
908 views

### Division by zero Java [closed]

The behavior of Java is explained in this topic. But, is Infinity useful for something? Float: public class DivisionByZeroFloat{ public static void main(String[] args) { System.out....
143 views

### How to properly decide what is the appropriate rounding off error for a mathematical function?

In the space of 3D geometry, I need to compute the magnitude of the cross product of two Line3D because I want to check whether these two Lines are "parallel" to each other. Line3D is consisted of 4 ...
88 views

### Where are mathematical equations applied in the application stack [closed]

Say I have a program using Java or C, that will interface with a hardware device and either read streaming data or write it to a database before applying a few complex mathematical equations to this ...
338 views

### How do I create a comparable checksum of a number sequence?

Sorry if the title is confusing, but here's an example to illustrate what I'm trying to accomplish. I would like to create a 'checksum' or ID grouping of similar number sequences, so that when you ...
328 views

### Interdependent variables

Let's say there are two variables a & b, both a & b would have a value between a predefined range. a = x1 to y1 (range) b = x2 to y2 (range) Variable a & b are interdependent, if the ...
123 views

### How a Proof Assistant Proves ∀ or ∃

Wondering how a proof assistant such as Coq proves forall or exists. For example: Three aspects: If you were to give it a huge set of items like a million, wondering if it would actually iterate ...
72 views

### Identify sets differing by one

I have a set of objects with different attributes; e.g. a set of cars with colors, brand etc. I choose subsets by virtue of a specific set of attributes. Now I want to identify pairs of such subsets ...
45 views

### Algorithm: Identify same Outlets / Supermarkets

We have a database with stores Outlets / Supermarkets (mainly in germany but other countries are also possible). We store some informations of this outlets / supermarkets like name, street, ...
17k views

### Is it good practice to replace division with multiplication when possible?

Whenever I need division, for example, condition checking, I would like to refactor the expression of division into multiplication, for example: Original version: if(newValue / oldValue >= ...
264 views

### How to model infinite non-linear combination? [closed]

Let L be an ordered set of positive integers (for example, the set of all primes). Here, #L = infinity, and N is a positive number serving as an upper limit. Goal is to list the following set M: M =...
142 views

### Use case, design, and how to append to an immutable object in functional programming

This is not (supposed to be) an opinion question, but it is a newbie question, so if there is just a resource I haven't found that I need to read, point me there :) I am in the design stages of a ...
196 views

### Handling behavior of non-finite numbers

Without using big int classes in C++, what's a good way to handle arithmetic on large numbers? For instance, writing a Vector class that deals with dot products and cross products using large ...
417 views

### Round robin, balanced home/away, multiple locations with multi-team options

This is my first question on this forum, have tried to exhaust every possible research option I could think of or find. Actually this is the first time I've posted for help with this anywhere, so ...
1k views

### What's the needed math for building algorithms? [closed]

What's the needed math for building algorithms? Because I was reading a book and I can't understand much. It says I need simple math from high school. I don't want to learn all the math that exist ...
310 views

### I loved developing a 2D game(C++ SDL), but i am not good at maths/physics [closed]

I developed 2 games in C++ using SDL. Without using any wrappers. I literally loved and enjoyed every part of the journey. Complex algorithms, how 2D works, rendering, audio, input etc. But i am not ...
75 views

### Set of items closest to the mean? [closed]

Given a set of N objects with assigned weights, how would we find the set of K objects that is closest to the average? The average being sum(weights) / N. Also, how could we compute the next set ...
147 views

### Memoization in case of recursive interdefined functions in Haskell/Functional Programming?

I was reading Memoization with recursion which tells how for a recursively defined function fun we can do memoization by: -- Memoization memoize f = (map f [0 ..] !!) -- Base cases g f 0 = 0 g f 1 = ...
1k views

### In Java, why does Integer.MIN_VALUE == -Integer.MIN_VALUE

Quite simply, I was aghast when I discovered one of my unit tests was failing because -Integer.MIN_VALUE == Integer.MIN_VALUE! Why would the language designers choose this, what is the mathematical ...
95 views

### How is the problem NOVICE43 on Sphere Online Judge(SPOJ) related to Bell Numbers?

Problem Statement : When I first learned backtracking I made a program to find all the permutations of the English alphabets in lexicographically increasing. Filled with elation I showed the ...
341 views

### What's the proper class hierarchy to use for matrices?

I'm working with particular classes of matrices which admit fast operations without resorting to dense linear algebra. To keep the heierarchy simple, I'm currently doing the following (greatly ...
335 views

### How do I unit test nuanced mathematical procedures?

I'm writing some code for a scientific simulation and I'd really like to use this as an opportunity to get some unit testing practice under my belt. I understand the idea of tests in theory, but I ...
116 views

### Find transformation function for point on an image

I am trying to develop an algorithm, but I barely can describe it so I'm not sure what to look for. I have two images img_A and img_B. img_A is the original, while img_B is an image of the same item ...
681 views

### Algorithm for windowed online covariance

I'm trying to adapt an algorithm to calculate covariance to work over a rolling window on the data. Wikipedia has an algorithm for online covariance: def online_covariance(data1, data2): mean1 = ...
5k views

### What is the mathematics foundation for first/second/third class values in programming languages?

Added Just found two related questions https://math.stackexchange.com/q/1759680/1281 https://stackoverflow.com/a/2582804/156458 In programming languages, from Michael Scott's Programming Language ...
4k views

### Why was the caret used for XOR instead of exponentiation?

Not that it's really a problem for anyone that has faced this syntactic issue before, but I see a wild amount of confusion stemming from the use of the caret (^) as the XOR operation in lieu of the ...
594 views

### Calculate largest square in rectangle with a given vertex

There are two points (x1, y1) and (x2, y2), each of which can be any real integer pair. These define a rectangle R with vertices {(x1, y1), (x2, y2), (x1, y2), (x2, y1)}. The rectangle exists in a ...
113 views

### Return random item by its weight, advanced level

There are many typical questions like Return random list item by its weight Imagine more advanced problem. You have N sources of pair (item_id, weight) information. Let's call them Shards. ...
332 views

### C++ Basic Rotation Question

I've got a problem and I haven't yet found an explained solution to get it drilled into my head: I want my object to make a basic rotation TOWARDS the mouse cursor, not the lock-on. I know it must be ...
825 views

### How can I create a set of pixel coordinates for a line in Python?

I've got some code that's searching pixel by pixel from a starting point, at a certain angle, until it finds a pixel (a non-white pixel) It only has to search around 300 pixels: I'm currently using ...