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# Rafael Hernandez-Walls

##### Last seen: ein Tag ago
1.132 total contributions since 2010

My interest is everything related to numerical schemes applied to PDE and Oceanography, UABC.

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Solved

Find the average of a random sequance
Write a function that generates random integers within a loop, and calculates the mean of the positive numbers only. At each ...

ein Tag ago

Solved

Horizontal matrix sort
Given a matrix x with n rows and m columns, return a matrix y with n rows and 2m columns, such that every row in x is sorted fro...

ein Tag ago

Solved

Find the index of nth maximum of a row vector of real numbers
Given a vector of real numbers x, find the index idx of _n_ th maximum value. If nth maximum occurs more than once, return the i...

ein Tag ago

Solved

Please check if calorie intake is less than 300 kcal.
I like eating some puddings and some chocolate cookies around 3 o'clock. However, I care about calorie intake. Please check whe...

ein Tag ago

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means
Calculate the arithmetic, the geometric and the harmonic mean of a given vector (with positive elements) and return them in a ve...

ein Tag ago

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Energy-Mass Equivalence
Given input enegy of the object, E, and constant c = 300,000,000, find the mass of the object.

ein Tag ago

Solved

Repetition of matrices
*A is a bold matrix: [1 2 3; 4 5 6;7 8 9]* Given an integer 'n' , a matrix B exists such that has n copies of A in the row an...

15 Tage 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...

23 Tage ago

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frame of the matrix
Given the matrix M, return M without the external frame.

23 Tage ago

Solved

Calculate Amount of Cake Frosting
Given two input variables |r| and |h|, which stand for the radius and height of a cake, calculate the surface area of the cake y...

25 Tage ago

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How long does it take to run a bath?
Given the *volume flow rate* (volume/time) of a faucet and the *volume* of a bath tub, find the amount of time it takes to fill ...

etwa ein Monat ago

Solved

R2012b atan in Degrees
Return in degrees the atan result of inputs for all four quadrants. *Examples:* [x, y] Degrees 1 0 0 1 1 ...

etwa ein Monat ago

finding all indices of a value in matrix
A=[2 2 3 ; 2 4 2; 2 3 2]; [r,c]=find(A==min(A))

etwa ein Monat ago | 0

| accepted

Solved

Remove duplicated triangles
Input T is a triangulation (triplet list of indices -positive integers-, each index refering to a vertex number in a correspondi...

4 Monate ago

Solved

Weighted moving average
x1=[1 2 1]; y1=[1 2 2 4 5 6 6 8]; Make function for weighted moving average. z(i)=(x1(i)*y1(i)+x1(i+1)*y1(i+1)+x1(i+2)*y1...

4 Monate ago

Solved

Height of a right-angled triangle
Given numbers a, b and c, find the height of the right angled triangle with sides a and b and hypotenuse c, for the base c. If a...

4 Monate ago

Solved

Separate even from odd numbers in a vector - with a loop
*Using a loop*, rearrange a vector of integers such that the odd numbers appear at the beginning, and even numbers at the end. T...

4 Monate ago

Solved

Angle of triangle
For three unknown points a b c, given three sides ab bc ca, find three angles abc bca cab in radians. Your function should b...

4 Monate ago

Solved

Find the Oldest Person in a Room
Given two input vectors: * |name| - user last names * |age| - corresponding age of the person Return the name of the ol...

4 Monate ago

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Compute Fibonacci Number
Compute the _n_-th Fibonacci Number f(0) = 0, f(1) = 1, f(2) = 1, f(3) = 2, ... f(42) = 267914296

4 Monate ago

Solved

Given a 4x4 matrix, swap the two middle columns
If a = [1 2 3 4; 1 2 3 4; 1 2 3 4; 1 2 3 4]; then the result is ans = 1 3 2 4 1 3 2...

4 Monate ago

Solved

Can we make a triangle?
Given three positive number, check whether a triangle can be made with these sides length or not. remember that in a triangle su...

4 Monate ago

Solved

Divisible by 10
Pursuant to the <http://www.mathworks.com/matlabcentral/cody/problems/42404-divisible-by-2 first problem> in this series, this o...

4 Monate ago

Solved

Perimeter of a semicircle
Given the diameter d, find the perimeter of a semicircle

4 Monate ago

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Write a function man that takes a row vector v and returns a matrix H as follows..
Write a function called man that takes a row vector v as an input and returns a matrix H whose first column consist of the eleme...

4 Monate ago

Solved

Get all prime factors
List the prime factors for the input number, in decreasing order. List each factor. If the prime factor occurs twice, list it as...

4 Monate 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 Monate 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 Monate ago

Solved

Convert from Fahrenheit to Celsius
Given an input vector |F| containing temperature values in Fahrenheit, return an output vector |C| that contains the values in C...

4 Monate ago

Solved

another bullseye
create matrix like below -- for x=2, y=[1 1 1 1 1; 1 2 2 2 1; 1 2 3 2...

4 Monate ago