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Rafael Hernandez-Walls


Last seen: Today
1,233 total contributions since 2010

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

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Solved


There are 10 types of people in the world
Those who know binary, and those who don't. The number 2015 is a palindrome in binary (11111011111 to be exact) Given a year...

21 hours ago

Solved


Relative ratio of "1" in binary number
Input(n) is positive integer number Output(r) is (number of "1" in binary input) / (number of bits). Example: * n=0; r=...

21 hours ago

Answered
¿Cómo puedo encontrar los indices de un arreglo con valores repetidos con la función find y operadores relacionales?
Yo pienso que si te interesan las posiciones de los valores es mejor poner lo siguiente: n=find((A<4)&(A~=0))

22 hours ago | 1

Answered
display result (numbers)
intent with the format command format long

2 days ago | 0

Answered
if greater than in for loop
seven=(seven>100).*(seven-25)+(seven<=100).*seven;

7 days ago | 0

Answered
Can someone rearrange the code to run
%subdivisions space /time ht=0.01; Tmax=1.2; nx=33; hx=1/(nx-1); x=[0:hx:1]'; %matrices K=stiff2(1/pi^2,hx,nx); M=mass(1/ht,h...

8 days ago | 0

| accepted

Answered
3d line plot help
Using this function: function Y = Piecewise(X1,X2) T = linspace(-7.5,17,120); N = length(T); for n = 1:N if X1(n) > 0 ...

8 days ago | 0

Answered
How to Rotate the Ellipses at calculated angle?
%cov is 2x2 covariance matrix that is generated through a long process t = 0:0.1:2*pi; %time axis %Xest is center of ellipse a...

14 days ago | 0

Answered
Function returning matrix instead of vector
f=@(xf,xdata)xf(1)*(xf(4)+((xf(2)-xdata)/(xf(3)/2))).^2./(1+((xf(2)-xdata)/(xf(3)/2)).^2)

15 days ago | 0

Answered
Missing inputs to distance function
First you need to put you trajectory of the directory, in my case I put this path(path,['/Users/rafaelhernandezwalls/Downloads/...

16 days ago | 0

Answered
Plotting with nested for loops
syms y t=[0 pi 2*pi]; a=[5 10]; for k=1:length(a) for j=1:length(t) f=a(k)*sin(t(j)*y); figure ...

16 days ago | 0

Answered
Plot solutions to a multi variable system: x + 2y + 3z = 4
if using mesh, and plot3 [y,z]=meshgrid(-4:.1:4,-4:.1:4); x=4-3*z-2*y; mesh(y,z,x) plot3(x,y,z,'o');

18 days ago | 1

| accepted

Solved


Binary code (array)
Write a function which calculates the binary code of a number 'n' and gives the result as an array(vector). Example: Inpu...

19 days ago

Answered
How do I get a loop to return all the values that I am looking for at one time?
e=0:200:11000; i=1:length(e) Re=6.37e6; g0=9.80665; g=g0*((Re^2)./((e(i)+Re).^2))

20 days ago | 1

Solved


Right Triangle Side Lengths (Inspired by Project Euler Problem 39)
If _p_ is the perimeter of a right angle triangle with integral length sides, { _a_, _b_, _c_ }, there are exactly three solutio...

20 days ago

Solved


Mid-term report
You just got your mid-term report, but it's full of ones and twos :(. So before you give it to your parents, you change it, in o...

21 days ago

Solved


Square
X is a number, write a code, where Y should be the square of X.

21 days ago

Solved


Square root
Given x (a matrix), give back another matrix, where all the elements are the square roots of x's elements.

21 days ago

Answered
Which method is MATLAB use in poly2 to do a curve fitting?
% -- FT is a string or a FITTYPE specifying the model to fit. % % If FT is a string, then it may be: % % FITTYPE ...

21 days ago | 0

Answered
how can I give each subplot a different title?
figure conRR=linspace(1,100,100); conRR(:,2)=sin(conRR(:,1)); conRR(:,3)=sin(conRR(:,1)); conRR(:,4)=sin(conRR(:,1)); conRR...

25 days ago | 0

Solved


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

25 days ago

Solved


Pad zero between every adjacent values of the vector.
you are given a vector x. you have to make an output vector y with zeros padded between every adjacent values of x. e.g x: ...

26 days ago

Solved


Times 10
Try out this test problem first. Given the variable x as your input, multiply it by ten and put the result in y. Examples:...

1 month ago

Solved


Find the mean of a 2-D matrix after excluding elements of specified sub-matrix
You need to find the mean of a 2-D matrix after excluding elements which form an inner sub-matrix. e.g. If the input 2-D matrix ...

1 month ago

Solved


Perimeter of a square!
Calculate the circumference of the square whose side is n

1 month ago

Solved


Find my daddy long leg (No 's')
Given the ratio of the two legs (longer / shorter), and the hypotenuse length, find the value of the bigger leg.

1 month ago

Solved


Get the area of ​​the square.
Four circles are inscribed in the square ABCD. The perimeter of each circle is *aπ*. <<http://imgfz.com/i/UzgCJut.png>> Gi...

2 months ago

Solved


Find the area of ​​the square
There are *n²* circles inscribed in the square ABCD. The perimeter of each circle is *aπ* <<http://imgfz.com/i/3wzCeAT.png>> ...

2 months ago

Solved


Spiral Out - 01
Create a spiral matrix ( clock-wise direction ) of size n. Try to do that without using the built-in function.

2 months ago

Solved


Compute the missing quantity among P, V, T for an ideal gas
Consider 100 mol of helium gas at a certain pressure (P), volume (V), and temperature (T). Assuming that the ideal gas law appli...

2 months ago

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