# Rafael Hernandez-Walls

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 ...

1 month 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...

1 month 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...

1 month 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...

1 month ago

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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...

1 month ago

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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?

1 month ago

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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; ...

1 month ago

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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...

3 months 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...

3 months ago

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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 ...

7 months ago

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...

1 year ago

Solved

mathematics , probability problem

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

1 year ago

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MATLAB Basics: Complex Conjugates

For a given complex number, x, return the complex conjugate, y.

1 year ago

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MATLAB Basics: Complex Numbers

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

1 year 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: ...

1 year ago

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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...

1 year ago

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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...

1 year ago

Solved

Calculate the answer to life the universe and everything

<https://en.wikipedia.org/wiki/42_(number)>

2 years ago

Solved

Simpsons's rule (but not Homer Simpson)

I wonder what Homer Simpson would have thought of Simpson's rule? Somehow I doubt his thoughts would have included the phrase Ne...

2 years ago