# Cullen Walsh

### UNC Chapel Hill

Physical Chemistry PhD

**Programming Languages:**

Java, MATLAB

**Spoken Languages:**

English

**Professional Interests:**

Physics, Chemistry, Material Sciences

**Statistics**

**Cody**

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**Content Feed**

Solved

"mirror" matrix

Create n x 2n "mirror" matrix of this type: Examples For n = 2 m = [ 1 2 2 1 1 2 2 1 ] For n = 3 m = ...

2 months ago

Solved

Create a Multiplication table matrix...

Create a product table in this format: P = [ 1 2 3 4 5; 2 4 6 8 10; 3 6 9 12 15; 4 8 12 1...

2 months ago

Solved

Remove NaN ?

input -> matrix (n*m) with at least one element equal to NaN; output -> matrix(p*m), the same matrix where we deleted the enti...

2 months ago

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Set some matrix elements to zero

First get the maximum of each *row*, and afterwards set all the other elements to zero. For example, this matrix: 1 2 3 ...

2 months ago

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Make an awesome ramp for a tiny motorcycle stuntman

Okay, given a vector, say v=[1 3 6 9 11], turn it into a matrix 'ramp' like so: m=[1 3 6 9 11; 3 6 9 11 0; 6 9 ...

2 months ago

Solved

Matrix with different incremental runs

Given a vector of positive integers a = [ 3 2 4 ]; create the matrix where the *i* th column contains the vector *1:a(i)...

2 months ago

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Back to basics 23 - Triangular matrix

Covering some basic topics I haven't seen elsewhere on Cody. Given an input matrix, return a matrix with all elements above a...

2 months ago

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Back to basics 21 - Matrix replicating

Covering some basic topics I haven't seen elsewhere on Cody. Given an input matrix, generate an output matrix that consists o...

2 months ago

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Find the maximum two numbers of every column of a matrix

Find the maximum two numbers of every column of a matrix. Example: If we input a matrix A = [ 1 2 4 6 0 3 ...

2 months ago

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Another colon problem

This is simple problem based on problems 555, 801, 1118, etc. Create an index vector from two input vectors. Example: ...

2 months ago

Solved

Replace pattern 0 1 0 and 1 0 1

Find and replace a pattern in a row of zeroes and ones. * Find 1 0 1 and replace it with 1 1 1 * Find 0 1 0 and replace it w...

2 months ago

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Side of an equilateral triangle

If an equilateral triangle has area A, then what is the length of each of its sides, x? <<https://i.imgur.com/jlZDHhq.png>> ...

2 months ago

Solved

Dimensions of a rectangle

The longer side of a rectangle is three times the length of the shorter side. If the length of the diagonal is x, find the width...

2 months ago

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Is this triangle right-angled?

Given three positive numbers a, b, c, where c is the largest number, return *true* if the triangle with sides a, b and c is righ...

2 months ago

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Find a Pythagorean triple

Given four different positive numbers, a, b, c and d, provided in increasing order: a < b < c < d, find if any three of them com...

2 months ago

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Is this triangle right-angled?

Given any three positive numbers a, b, c, return true if the triangle with sides a, b and c is right-angled. Otherwise, return f...

2 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...

2 months ago

Solved

Side of a rhombus

If a rhombus has diagonals of length x and x+1, then what is the length of its side, y? <<https://imgur.com/x6hT6mm.png>> ...

2 months ago

Solved

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...

2 months ago

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There are 10 types of people in the world

Those who know binary, and those who don't. The number 2015 is a palindrome in binary (11111011111 to be exact) Given a year...

2 months ago

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Converting binary to decimals

Convert binary to decimals. Example: 010111 = 23. 110000 = 48.

2 months ago

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Binary code (array)

Write a function which calculates the binary code of a number 'n' and gives the result as an array(vector). Example: Inpu...

2 months ago

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Relative ratio of "1" in binary number

Input(n) is positive integer number Output(r) is (number of "1" in binary input) / (number of bits). Example: * n=0; r=...

2 months ago

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Bit Reversal

Given an unsigned integer _x_, convert it to binary with _n_ bits, reverse the order of the bits, and convert it back to an inte...

2 months ago

Solved

Given an unsigned integer x, find the largest y by rearranging the bits in x

Given an unsigned integer x, find the largest y by rearranging the bits in x. Example: Input x = 10 Output y is 12 ...

2 months ago

Solved

Binary numbers

Given a positive, scalar integer n, create a (2^n)-by-n double-precision matrix containing the binary numbers from 0 through 2^n...

2 months ago

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Find the largest value in the 3D matrix

Given a 3D matrix A, find the largest value. Example >> A = 1:9; >> A = reshape(A,[3 1 3]); >> islargest(A) a...

2 months ago

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Generate N equally spaced intervals between -L and L

Given N and L, return a list of numbers (in ascending order) that divides the interval [-L L] into N equal-length segments. F...

2 months ago

Solved

We love vectorized solutions. Problem 1 : remove the row average.

Given a 2-d matrix, remove the row average from each row. Your solution MUST be vectorized. The solution will be tested for ac...

2 months ago

Solved

First non-zero element in each column

For a given matrix, calculate the index of the first non-zero element in each column. Assuming a column with all elements zero i...

2 months ago