Questions tagged [inversion]

The inversion tag is most often used with postings about matrix inversion or data transformations of a similar nature such as color inversion. In addition to the [inversion] tag, you should also specify a tag that indicates the nature of the inversion such as [matrix] or [colors] as most people will do a search not only on the tag [inversion] but also a qualifying tag indicating the kind of inversion.

Inversion in a sequence (A1 . . . An) of n distinct numbers is a pair (i, j) such that i < j and Ai > Aj.
Inversion number of a sequence is one common measure of its sortedness.

Inversion is a general purpose tag indicating a type of transformation to data whether that data is in the form of a matrix, an image (can be considered a matrix of pixels with color values), or some other form of structured data.

When using the [inversion] tag also provide a qualifying tag such as [matrix] or [colors] or other tag which indicates the kind or type of data that is being inverted.

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Inversion count for 100000 integers using merge sort reading from a text file. But not able to get the correct inversion count

Below is the code I have written to read the 100000 integers from a text file and to sort them using merge sort. Issues: The sorted integers are getting displayed in correct order only in the eclipse console, but when I try to write them to an…
Ram
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Sci-Kit Scaler and Inversion Does Not Yield Identical Numbers?

A bit new to Sci-kit, but noticing some behavior that seems a bit strange with minmax normalization and inversion (but maybe this is the intended behavior??). I thought when inverting I would re-generate the original datapoints - but instead the…
The Rhyno
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how to get inversion count with update

Inversion count in an given array is a very famous with a time complexity of O(NlogN). However, I wonder whether there is a way to do it with update. Input format: first line consist of an integer n; second line includes n integer which is the…
Brian Lee
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Performance question: Inverting an array of pointers in-place vs array of values

The background for asking this question is that I am solving a linearized equation system (Ax=b), where A is a matrix (typically of dimension less than 100x100) and x and b are vectors. I am using a direct method, meaning that I first invert A, then…
Anders
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How to improve my Java code for simulation from Gaussian (0,1)

I'm really new to java, I've created a code for simulating 100000 observations from Gaussian distribution with mean =0 and standard deviation=1 via inversion method. The code is slow compared to simulating with the rnorm command in R, or…
Alex
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Counting the number of inversions in merge sort

I have implemented a merge sort and, as well as sorting, I would like it to compute the number of inversions in the original array. Below is my attempt at implementing it, which for some reason doesn't compute the number of inversions…
Bruno Santos
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The algorithm inverse number

Is this a formula for the inverse number? eg 123-321? Number is K inv K= K%100 + K/10%10 * 10 + K % 10 *100 I'm not sure I exactly wrote, and I need this right for the task at school for graphic algorithm Edit:Yes i'm stupid xD I'm Beginner xD
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Error in running matrix inversion function in R

I am trying to inverse a matrix using two sets of functions :- Code is :- (comments describe the process) ## This function creates a special "matrix" object that can cache its inverse. makeCacheMatrix <- function(x = matrix()) { m <- NULL set <-…
Rishab Verma
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Issues with Inversion Count MergeSort Algorithm- Python

I am trying to count inversion from a file using MergeSort, and my code seems to work for smaller files, but bigger files produce the wrong output. My code: InversionCount.py: count = 0 def merge_sort_inversions(numberlist): if len(numberlist)…
vibhu1201
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Number of inversions in array

I am trying to find out the number of inversion in any array. I have applied mergesort. And when merging the sub arrays I counted the number if any value of right subarray is less than any value of left sub array. This code does not work if the…
user6423594
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(R) Error in solve() 'a' must be a numeric matrix

Here's the problem: I want to calculate the inverse of a 3x3 matrix. I tried to use solve(J), but it gives an error message: Error in solve.default(J) : 'a' must be a numeric matrix. Here's the matrix J and the…
Eduardo GS
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Converting permutation to inversion representation

Permutation P = [a1, a2, ... , aN] of the first N natural numbers can be represented by a list of inversions I = [i1, i2, ... , iN], where iK tells us how many numbers that are greater than K can be found before K in the permutation P. Example: if P…
Antoine
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Inversion for insertion sort!

This a question I found in the Wikipedia site (I want to learn sort algorithms very well). Anyway, this is a question - could you explain to me how I can show it? Exercise: Show that Algorithm Insertion Sort (A) runs in time O(n + I) given that I is…
user355002
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My Genetic Algorithm Program is not converging beyond a certain level of fitness

I am trying to write a genetic algorithm program for paleo-stress inversion i.e. from a given set of data I want to calculate the stress tensor.(Minimization problem) I have generated a synthetic data set for testing but it is not giving me desired…
Prithvi Thakur
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refine merge-sort to count number of inversions

I'm working on an improved version of merge sort so that it counts the number of inversions. Note: I don't want you to get my homework done, but I have some ideas about this and would love to know whether they make sense at all. As merge-sort is…
Andrew Tobey
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