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Rafael Rojas


Last seen: 22 days ago
35 total contributions since 2020

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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...

4 months ago

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Remove the vowels
Remove all the vowels in the given phrase. Example: Input s1 = 'Jack and Jill went up the hill' Output s2 is 'Jck nd Jll wn...

4 months ago

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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...

4 months ago

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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 + ...

4 months ago

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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...

4 months ago

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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...

4 months ago

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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...

4 months ago

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Find the longest sequence of 1's in a binary sequence.
Given a string such as s = '011110010000000100010111' find the length of the longest string of consecutive 1's. In this examp...

4 months ago

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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...

4 months ago

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Remove all the consonants
Remove all the consonants in the given phrase. Example: Input s1 = 'Jack and Jill went up the hill'; Output s2 is 'a ...

4 months ago

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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...

4 months ago

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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...

4 months ago

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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...

4 months ago

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

4 months ago

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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...

4 months ago

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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...

4 months ago

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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...

4 months ago

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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 ...

4 months ago

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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...

4 months ago

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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 ...

4 months ago

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Longest run of consecutive numbers
Given a vector a, find the number(s) that is/are repeated consecutively most often. For example, if you have a = [1 2 2 2 1 ...

4 months ago

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Rescale Scores
Each column (except last) of matrix |X| contains students' scores in a course assignment or a test. The last column has a weight...

4 months ago

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Calculate Inner Product
Given two input matrices, |x| and |y|, check if their inner dimensions match. * If they match, create an output variable |z|...

4 months ago

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Find MPG of Lightest Cars
The file |cars.mat| contains a table named |cars| with variables |Model|, |MPG|, |Horsepower|, |Weight|, and |Acceleration| for ...

4 months ago

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Find the Best Hotels
Given three input variables: * |hotels| - a list of hotel names * |ratings| - their ratings in a city * |cutoff| - the rat...

4 months ago

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Crop an Image
A grayscale image is represented as a matrix in MATLAB. Each matrix element represents a pixel in the image. An element value re...

4 months ago

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Calculate BMI
Given a matrix |hw| (height and weight) with two columns, calculate BMI using these formulas: * 1 kilogram = 2.2 pounds * 1 ...

4 months ago

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Plot Damped Sinusoid
Given two vectors |t| and |y|, make a plot containing a blue ( |b| ) dashed ( |--| ) line of |y| versus |t|. Mark the minimum...

4 months ago

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Calculate a Damped Sinusoid
The equation of a damped sinusoid can be written as |y = A.&#8519;^(-&lambda;t)*cos(2πft)| where |A|, |&lambda;|, and |f| ...

4 months ago

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Solve a System of Linear Equations
*Example*: If a system of linear equations in _x&#8321_ and _x&#8322_ is: 2 _x&#8321;_ + _x&#8322;_ = 2 _x&#8321;...

4 months ago

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