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Justin Dubin


Active since 2017

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Question


Trouble pivoting large table using unstack function
I have a large table (6307840x42) that I need to pivot. To scale down the problem, let's assume the table looks something like t...

meer dan 5 jaar ago | 1 answer | 0

1

answer

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Sum all integers from 1 to 2^n
Given the number x, y must be the summation of all integers from 1 to 2^x. For instance if x=2 then y must be 1+2+3+4=10.

meer dan 6 jaar ago

Solved


Weighted average
Given two lists of numbers, determine the weighted average. Example [1 2 3] and [10 15 20] should result in 33.333...

meer dan 6 jaar ago

Solved


Finding Perfect Squares
Given a vector of numbers, return true if one of the numbers is a square of one of the other numbers. Otherwise return false. E...

meer dan 6 jaar ago

Question


I want to extract a circle of values from a meshgrid
I have a 2D meshgrid with dimensions of distance x distance. I want to know the values at a fixed radius from the center.

meer dan 6 jaar ago | 2 answers | 0

2

answers

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Counting Money
Add the numbers given in the cell array of strings. The strings represent amounts of money using this notation: $99,999.99. E...

ongeveer 7 jaar ago

Solved


Bullseye Matrix
Given n (always odd), return output a that has concentric rings of the numbers 1 through (n+1)/2 around the center point. Exampl...

meer dan 7 jaar ago

Solved


Summing digits
Given n, find the sum of the digits that make up 2^n. Example: Input n = 7 Output b = 11 since 2^7 = 128, and 1 + ...

meer dan 7 jaar ago

Solved


Create times-tables
At one time or another, we all had to memorize boring times tables. 5 times 5 is 25. 5 times 6 is 30. 12 times 12 is way more th...

meer dan 7 jaar ago

Solved


Determine whether a vector is monotonically increasing
Return true if the elements of the input vector increase monotonically (i.e. each element is larger than the previous). Return f...

meer dan 7 jaar ago

Solved


Return the 3n+1 sequence for n
A Collatz sequence is the sequence where, for a given number n, the next number in the sequence is either n/2 if the number is e...

meer dan 7 jaar ago

Solved


Remove any row in which a NaN appears
Given the matrix A, return B in which all the rows that have one or more <http://www.mathworks.com/help/techdoc/ref/nan.html NaN...

meer dan 7 jaar ago

Solved


Times 2 - START HERE
Try out this test problem first. Given the variable x as your input, multiply it by two and put the result in y. Examples:...

meer dan 7 jaar ago

Solved


Is my wife right?
Regardless of input, output the string 'yes'.

meer dan 7 jaar ago

Solved


Swap the first and last columns
Flip the outermost columns of matrix A, so that the first column becomes the last and the last column becomes the first. All oth...

meer dan 7 jaar ago

Solved


Find all elements less than 0 or greater than 10 and replace them with NaN
Given an input vector x, find all elements of x less than 0 or greater than 10 and replace them with NaN. Example: Input ...

meer dan 7 jaar ago

Solved


Return the largest number that is adjacent to a zero
This example comes from Steve Eddins' blog: <http://blogs.mathworks.com/steve/2009/05/27/learning-lessons-from-a-one-liner/ Lear...

meer dan 7 jaar ago

Solved


Back and Forth Rows
Given a number n, create an n-by-n matrix in which the integers from 1 to n^2 wind back and forth along the rows as shown in the...

meer dan 7 jaar ago

Solved


Fibonacci sequence
Calculate the nth Fibonacci number. Given n, return f where f = fib(n) and f(1) = 1, f(2) = 1, f(3) = 2, ... Examples: Inpu...

meer dan 7 jaar ago

Solved


Find the numeric mean of the prime numbers in a matrix.
There will always be at least one prime in the matrix. Example: Input in = [ 8 3 5 9 ] Output out is 4...

meer dan 7 jaar ago

Solved


Who Has the Most Change?
You have a matrix for which each row is a person and the columns represent the number of quarters, nickels, dimes, and pennies t...

meer dan 7 jaar ago

Solved


Make a checkerboard matrix
Given an integer n, make an n-by-n matrix made up of alternating ones and zeros as shown below. The a(1,1) should be 1. Examp...

meer dan 7 jaar ago

Solved


Triangle Numbers
Triangle numbers are the sums of successive integers. So 6 is a triangle number because 6 = 1 + 2 + 3 which can be displa...

meer dan 7 jaar ago

Solved


Column Removal
Remove the nth column from input matrix A and return the resulting matrix in output B. So if A = [1 2 3; 4 5 6]; and ...

meer dan 7 jaar ago

Solved


Select every other element of a vector
Write a function which returns every other element of the vector passed in. That is, it returns the all odd-numbered elements, s...

meer dan 7 jaar ago

Solved


Pizza!
Given a circular pizza with radius _z_ and thickness _a_, return the pizza's volume. [ _z_ is first input argument.] Non-scor...

meer dan 7 jaar ago

Solved


Determine if input is odd
Given the input n, return true if n is odd or false if n is even.

meer dan 7 jaar ago

Solved


Add two numbers
Given a and b, return the sum a+b in c.

bijna 8 jaar ago

Solved


Find the sum of all the numbers of the input vector
Find the sum of all the numbers of the input vector x. Examples: Input x = [1 2 3 5] Output y is 11 Input x ...

bijna 8 jaar ago

Solved


Make the vector [1 2 3 4 5 6 7 8 9 10]
In MATLAB, you create a vector by enclosing the elements in square brackets like so: x = [1 2 3 4] Commas are optional, s...

bijna 8 jaar ago