Questions tagged [math]

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

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3
votes
1answer
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 ...
-3
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1answer
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 ...
-5
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1answer
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 ...
0
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2answers
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 ...
1
vote
2answers
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 ...
-1
votes
1answer
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 ...
2
votes
3answers
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, ...
1
vote
1answer
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 ...
24
votes
4answers
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,...
7
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1answer
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 ...
3
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3answers
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 ...
-4
votes
2answers
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 ...
-3
votes
2answers
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 "...
2
votes
1answer
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 ...
2
votes
1answer
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 ...
2
votes
3answers
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 ...
0
votes
1answer
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 ...
0
votes
1answer
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 ...
0
votes
1answer
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 ...
2
votes
0answers
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....
3
votes
4answers
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 ...
-2
votes
1answer
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 ...
1
vote
1answer
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 ...
-1
votes
1answer
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 ...
0
votes
1answer
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 ...
-3
votes
1answer
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 ...
1
vote
1answer
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, ...
72
votes
10answers
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 >= ...
-3
votes
2answers
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 =...
0
votes
3answers
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 ...
2
votes
2answers
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 ...
0
votes
1answer
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 ...
-3
votes
1answer
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 ...
-3
votes
1answer
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 ...
-6
votes
1answer
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 ...
0
votes
1answer
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 = ...
3
votes
3answers
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 ...
0
votes
1answer
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 ...
6
votes
3answers
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 ...
3
votes
2answers
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 ...
2
votes
1answer
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 ...
2
votes
2answers
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 = ...
19
votes
6answers
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 ...
36
votes
1answer
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 ...
0
votes
1answer
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 ...
0
votes
1answer
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. ...
-1
votes
1answer
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 ...
0
votes
1answer
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 ...
4
votes
4answers
2k views

Why are arbitrary-precision decimals used over rational numbers in practice?

The basic arithmetic a computer chip can do only works on numbers(integers or floating point) of a fixed size. There are many algorithms that could be extended to work on numbers of arbitrary size (...
-3
votes
3answers
2k views

How to use units for a slope calculation?

Simple question: is the result of a slope calculation in Python (say, stats.linregress() function) in units of radians, or unitless (e.g. what's 18 deg or 0.314 rad would be equivalent to 0.2 in the ...

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