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# Da Lu

90 total contributions since 2018

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Extra safe primes
Did you know that the number 5 is the first safe prime? A safe prime is a prime number that can be expressed as 2p+1, where p is...

alrededor de 1 año ago

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Return a list sorted by number of occurrences
Given a vector x, return a vector y of the unique values in x sorted by the number of occurrences in x. Ties are resolved by a ...

más de 1 año ago

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Reverse Run-Length Encoder
Given a "counting sequence" vector x, construct the original sequence y. A counting sequence is formed by "counting" the entrie...

más de 1 año ago

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Triangle sequence
A sequence of triangles is constructed in the following way: 1) the first triangle is Pythagoras' 3-4-5 triangle 2) the s...

más de 1 año 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...

más de 1 año 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...

más de 1 año 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...

más de 1 año 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. <<http://upload...

más de 1 año ago

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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...

más de 1 año ago

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Side of a rhombus
If a rhombus has diagonals of length x and x+1, then what is the length of its side, y? <<http://upload.wikimedia.org/wikipe...

más de 1 año 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? <<http://upload.wikimedia.org/wikipe...

más de 1 año ago

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Area of an equilateral triangle
Calculate the area of an equilateral triangle of side x. <<http://upload.wikimedia.org/wikipedia/commons/e/e0/Equilateral-tr...

más de 1 año ago

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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...

más de 1 año ago

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De-dupe
Remove all the redundant elements in a vector, but keep the first occurrence of each value in its original location. So if a =...

más de 1 año ago

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No Twins?
Write a function that accepts as input a vector and returns the same vector, but retaining only the first occurrence of an eleme...

más de 1 año ago

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Roll the Dice!
*Description* Return two random integers between 1 and 6, inclusive, to simulate rolling 2 dice. *Example* [x1,x2] =...

más de 1 año ago

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Too mean-spirited
Find the mean of each consecutive pair of numbers in the input row vector. For example, x=[1 2 3] ----> y = [1.5 2.5] x=[1...

más de 1 año ago

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You just measured its surface area, that is the input.

más de 1 año 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. <<http://upload....

más de 1 año ago

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Swap the input arguments
Write a two-input, two-output function that swaps its two input arguments. For example: [q,r] = swap(5,10) returns q = ...

más de 1 año ago

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Bottles of beer
Given an input number representing the number of bottles of beer on the wall, output how many are left if you take one down and ...

más de 1 año ago

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Distance walked 1D
Suppose you go from position 7 to 10 to 6 to 4. Then you have walked 9 units of distance, since 7 to 10 is 3 units, 10 to 6 is 4...

más de 1 año ago

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How to find the position of an element in a vector without using the find function
Write a function posX=findPosition(x,y) where x is a vector and y is the number that you are searching for. Examples: fin...

más de 1 año ago

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Reverse the vector
Reverse the vector elements. Example: Input x = [1,2,3,4,5,6,7,8,9] Output y = [9,8,7,6,5,4,3,2,1]

más de 1 año 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...

más de 1 año ago

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Calculate the Hamming distance between two strings
Inspired by a similar Cody problem found <http://www.mathworks.com/matlabcentral/cody/problems/93-calculate-the-levenshtein-dist...

más de 1 año ago

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Compute the step response of a DC motor
Compute the step response of a DC motor shown below <<http://blogs.mathworks.com/images/seth/cody/dc-motor.png>> The param...

casi 2 años ago

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Make a low pass filter
Make a first order low pass filter that will filter out the high frequency oscillations for the given input signal. The cut-off ...

casi 2 años ago

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Produce a Fibonacci sequence
Construct a diagram that generates the Fibonacci sequence: 1, 1, 2, 3, 5, 8, 13, 21, 34.....up to 377 The Fibonacci sequ...

casi 2 años ago

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Model a simple pendulum
Model a simple pendulum of length 200cm with bob of mass 100g and plot the position in degrees. The pendulum starts at 30 degree...

casi 2 años ago