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Rafael Hernandez-Walls


Last seen: 5 maanden ago |  Active since 2010

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

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Solved


Molar Air Density from Temperature and Pressure
The molar density of air can be found from the Temperature and Pressure using the ideal gas law. where the Molar density STP ...

7 maanden ago

Solved


Calculate Wind Chill Factor
The NWS Wind Chill Temperature (WCT) index formula for calculating the dangers from winter winds and freezing temperatures: Cal...

7 maanden ago

Solved


Air Mass to Star for an Observer at Mean Sea Level
Air mass is a measure of how much atmosphere light from a source above the atmosphere (eg sun, planet, star) has to travel throu...

7 maanden ago

Solved


Find Air Temperature from Cricket Stridulation Rate
Stridulation is the process that creates a cricket's “chirp” by rubbing their wings or legs. According to the Old Farmer's Alma...

7 maanden ago

Solved


Construyendo matrices parte 2
Construye la siguiente matriz a partir de otros tres vectores/matrices. [ 1 8 15 3 3 3 3 2 9 16 3 3...

7 maanden ago

Solved


Sum of series IV
What is the sum of the following sequence: Σ(-1)^(k+1) (2k-1)^2 for k=1...n for different n?

7 maanden ago

Solved


Back to basics 22 - Rotate a matrix
Covering some basic topics I haven't seen elsewhere on Cody. Rotate the input matrix 90 degrees counterclockwise (e.g. [1 2; ...

8 maanden ago

Solved


Composite Trapezoidal Rule for Numeric Integration
Use the trapezoidal rule to numerically integrate a function, _f(x)_, passed as the first argument, between upper and lower limi...

9 maanden ago

Solved


Differential equations I
Given a function handle |f| an initial condition |y0| and a final time |tf|, solve numerically the differential equation dy...

9 maanden ago

Solved


Weighted Convolution
Given two input vectors x = [x_1, x_2, ..., x_K] and y = [y_1, y_2, ..., y_K] of equal length, compute the weighted convolution ...

ongeveer een jaar ago

Answered
Determine if any key is being pressed
If only use the function: pause

meer dan een jaar ago | 0

Solved


The Piggy Bank Problem
Given a cylindrical piggy bank with radius g and height y, return the bank's volume. [ g is first input argument.] Bonus though...

meer dan een jaar ago

Solved


mathematics , probability problem
How many different result can we have, rolling k dice?

bijna 2 jaar ago

Solved


MATLAB Basics: Complex Conjugates
For a given complex number, x, return the complex conjugate, y.

bijna 2 jaar ago

Solved


MATLAB Basics: Complex Numbers
For a given complex number, x, return the real and imaginary parts as a vector, y = [Real Imaginary].

bijna 2 jaar ago

Solved


Flip coins

bijna 2 jaar ago

Solved


Normalizing a vector

bijna 2 jaar ago

Solved


Return fibonacci sequence do not use loop and condition
Calculate the nth Fibonacci number. Given n, return f where f = fib(n) and f(1) = 1, f(2) = 1, f(3) = 2, ... Examples: ...

bijna 2 jaar ago

Solved


Number of Even Elements in Fibonacci Sequence
Find how many even Fibonacci numbers are available in the first d numbers. Consider the following first 14 numbers 1 1 2...

bijna 2 jaar ago

Solved


Find the next Fibonacci number
In the sequence of Fibonacci numbers, every number is the sum of the two preceding ones: 1, 1, 2, 3, 5, 8, 13, 21, 34, 55...

bijna 2 jaar ago

Answered
matlab not plotting graph
You need one point in the equation of z h = [2,4,6,8,10]; x = 10.1; y = 2.5; z = (x * h.^2 - x - sqrt(y^2*h.^2 - y^2))./ (h....

bijna 2 jaar ago | 0

Solved


Mass Conversion 1

bijna 2 jaar ago

Answered
how i can find the chessboard lines and draw on the main image with any solution
Maybe you can use the Radon Transform, like this link: https://www.mathworks.com/help/images/detect-lines-using-the-radon-trans...

bijna 2 jaar ago | 0

Answered
how can I get y which correspond to x and then plot (x,y)??
Try this: x=linspace(-4,4); for r=1:length(x) y(r)=fzero(@(y)y.^3+0.2*exp(-1*x(r).^2)*y.^2-2.2039*y.^2+0.8155,1); end p...

bijna 2 jaar ago | 0

Answered
How to read data from text file and store as it is with variables
Assuming you have a file with only following line (name of file= 'algo.txt'): phi1_32_1 = 1 You could then read the line with...

bijna 2 jaar ago | 0

Answered
numerical simulation of travelling wave of epidemic model
try this.... clear all; xl=0; xr=1; %domain[xl,xr] J=1000; % J: number of dividion for x dx=(x...

ongeveer 2 jaar ago | 0

Answered
Read a txt file
try this Dens1 = [A(:,1),9.11*A(:,2).^(1.326)]; fileID1=fopen('E1.txt','w'); % [n,~]=size(Dens1); for k=1:n b=fprintf(...

ongeveer 2 jaar ago | 0

Answered
How to display correlation coefficents on plot?
you can try something like this: x = [0 0.000009 0.000018 0.000028 0.000037 0.000046 0.000055 0.000065 0.000074 0.000083 0.0000...

ongeveer 2 jaar ago | 0

Answered
extracting value from a matrix
I think it is better to put the variable X as a string and from there start. for example: X=['1000000000000000000000000000000...

ongeveer 2 jaar ago | 0

| accepted

Answered
How to get Taylor polynomial for functions?
You can use a function that is in the MAThWORKS fileexchange (I put the link): str=input('Function? ','s'); %tray with: cos(x)...

ongeveer 2 jaar ago | 0

| accepted

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