# Are Mjaavatten

Retired physicist with background in the petroleum and process industry. My main interests are mathematical modelling, numerical methods, and thermodynamics.

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Thermodynamic models and tools. H2O, H2, CO2, air, and more

Tool for effective, high-precision thermodynamic calculations. Available species are H2, paraH2, orthoH2, N2, O2, Ar, H2O, and C...

24 days ago | 20 downloads |

Solved

Max index of 3D array

Given a three dimensional array M(m,n,p) write a code that finds the three coordinates x,y,z of the Maximum value. Example ...

4 months ago

Solved

Determine the number of odd integers in a vector

Determine the number of unique odd integers in a vector. Examples: Input x = [2 5 8 3 7 1]; Output y = 4; Inp...

4 months ago

Solved

Reference Index Number

Given a reference set R of elements (each unique but identical in type), and a list V of elements drawn from the set R, possibly...

4 months ago

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Change the sign of even index entries of the reversed vector

change the signs of the even index entries of the reversed vector example 1 vec = [4 -1 -2 9] ans = [9 2 -1 -4] example2...

4 months ago

Solved

Generate a vector like 1,2,2,3,3,3,4,4,4,4

Generate a vector like 1,2,2,3,3,3,4,4,4,4 So if n = 3, then return [1 2 2 3 3 3] And if n = 5, then return [1 2 2 3 3 3 4...

4 months ago

Solved

Set a diagonal

Given a matrix M, row vector v of appropriate length, and diagonal index d (where 0 indicates the main diagonal and off-diagonal...

4 months ago

Solved

Create a vector whose elements depend on the previous element

The idea is to create a vector A whose elements depend on the previous element : *A(i+1) = 2*A(i)+1* *2 Inputs*: - A : The...

4 months ago

Solved

Finding peaks

Find the peak values in the signal. The peak value is defined as the local maxima. For example, x= [1 12 3 2 7 0 3 1 19 7]; ...

5 months ago

Solved

Implement a bubble sort technique and output the number of swaps required

A bubble sort technique compares adjacent items and swaps them if they are in the wrong order. This is done recursively until al...

5 months ago

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Decimation - Optimized for speed

This problem is similar to http://www.mathworks.com/matlabcentral/cody/problems/1092-decimation, only this time the score will b...

5 months ago

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Create an n-by-n null matrix and fill with ones certain positions

The positions will be indicated by a z-by-2 matrix. Each row in this z-by-2 matrix will have the row and column in which a 1 has...

5 months ago

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Getting the indices from a vector

This is a basic MATLAB operation. It is for instructional purposes. --- You may already know how to <http://www.mathworks....

5 months ago

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Unique values without using UNIQUE function

You must return unique values in a vector in *stable* mode without using the unique function. About stable order flag: ...

5 months ago

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Find nth maximum

Find nth maximum in a vector of integer numbers. Return NaN if no such number exists. x = [2 6 4 9 -10 3 1 5 -10]; So ...

5 months ago

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Create an index-powered vector

Given a input vector x, return y as index-powered vector as shown below. Example x = [2 3 6 9] then y should be [...

5 months ago

Solved

Find last zero for each column

Given a numeric array of arbitrary size, return the row index of the last zero for each column. If a column contains all nonzero...

5 months ago

Solved

Calculate the Number of Sign Changes in a Row Vector (No Element Is Zero)

For a row vector: V=[7 1 2 -3] there is one sign change (from 2 to -3). So, the function you write must return N=1. F...

5 months ago

Solved

Oh Zero Zero Zero!!!

Hello all, So you have to find the largest section of zeros in a vector and then find the length of those zeros and there start...

5 months ago

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Spot the rectangle

This problem is related to the 17x17 challenge. Given a matrix filled with ones and zeros, determine whether or not any rectangl...

5 months ago

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Length of the hypotenuse

Given short sides of lengths a and b, calculate the length c of the hypotenuse of the right-angled triangle. <<https://i.imgu...

5 months ago

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Area of an equilateral triangle

Calculate the area of an equilateral triangle of side x. <<https://i.imgur.com/jlZDHhq.png>> Image courtesy of <http://up...

5 months ago

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Area of an Isoceles Triangle

An isosceles triangle has equal sides of length x and a base of length y. Find the area, A, of the triangle. <<https://imgur...

5 months ago

Solved

Sum of series I

What is the sum of the following sequence: Σ(2k-1) for k=1...n for different n?

5 months ago

Solved

Length of a short side

Calculate the length of the short side, a, of a right-angled triangle with hypotenuse of length c, and other short side of lengt...

5 months ago

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Finding valleys

You have a vector of altitudes (units are arbitrary) and need to find the depths of all the valleys. You also need to determine ...

5 months ago

Solved

Knight Moves?

One of my favorite games are chess. Let’s do something with chess. If you don’t know chess, that’s completely fine. You can stil...

5 months ago

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Zero finder

Write a function named 'zero_finder' that takes a matrix as input and returns the row index of the last zero for each for each c...

5 months ago

Solved

Sequence Vectorization - I

Given a Natural number N, return the sequence - [1 1 2 1 2 3 1 2 3 4 ... 1 2 3 ... N-3 N-2 N-1 N] i.e. the horizontal concatenat...

5 months ago

Solved

Given a string s, find the length of the longest substring without repeating characters.

Given a string s, find the length of the longest substring without repeating characters. Example 1: Input: s = "abcabcbb" O...

5 months ago