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Sam McDonald

MathWorks

Last seen: 5 years ago |  Active since 2016

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I'm an Application Support Engineer at MathWorks and a Mechanical Engineer by education.

I enjoy recording/mixing new music and outdoor exploration.
Professional Interests: MATLAB and Simulink

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

7 years ago

Solved


Sort a list of complex numbers based on far they are from the origin.
Given a list of complex numbers z, return a list zSorted such that the numbers that are farthest from the origin (0+0i) appear f...

8 years ago

Solved


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

8 years 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...

8 years 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 + ...

8 years ago

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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...

8 years ago

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Simple equation: Annual salary
Given an hourly wage, compute an annual salary by multiplying the wage times 40 and times 50, because salary = wage x 40 hours/w...

8 years 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...

8 years ago

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Most nonzero elements in row
Given the matrix a, return the index r of the row with the most nonzero elements. Assume there will always be exactly one row th...

8 years 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...

8 years 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...

8 years 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...

8 years ago

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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...

8 years 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...

8 years 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...

8 years 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...

8 years 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 ...

8 years 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...

8 years 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...

8 years 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...

8 years ago

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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 ...

8 years ago

Solved


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

8 years ago

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Multiply by 3
Given the variable x as your input, multiply it by three and put the result in y.

8 years ago

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Add 7
Given an input variable x, output a variable y that is 7 greater than x. Example: Input x = 1 Output y is 8 Input ...

8 years ago

Solved


Create a two dimensional zero matrix
You have to create a zero matrix of size (mxn) whose inputs are m and n and the elements of your matrix should be zeros. Exam...

8 years ago

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find the maximum element of the matrix
for e.g x = [1 2; 3 4] y = 4

8 years 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 ...

8 years ago

Solved


Close MATLAB with keyboard
Close MATLAB with keyboard without using mouse

8 years 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...

8 years 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:...

8 years ago