William

Last seen: Today | Active since 2012

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Semi-retired physicist with interests in numerical modeling and mathematics.

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Count the peaceful queens
In a 5x5 chessboard with a queen of one color (white, say) on the perimeter, one can place 12 black queens on the board such tha...

3 days ago

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test
test

11 days ago

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Find the length of stream affected by a spill
When a contaminant is spilled into a stream, one might want to know how much of the stream is affected—e.g., the length over whi...

19 days ago

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Evaluate the generalized hypergeometric function
The <https://en.wikipedia.org/wiki/Generalized_hypergeometric_function generalized hypergeometric function> is defined as <<...

20 days ago

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List odd twin composites
Twin primes, or prime numbers that differ by 2 (e.g., 17 and 19, 59 and 61, or 191 and 193), are the subject of several Cody pro...

20 days ago

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Hyperperfect Numbers
A k-hyperperfect number is a natural number n for which the equality n = 1 + k(σ(n) − n − 1) holds, where σ(n) is the divisor ...

21 days ago

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Count the ways to make Scorigami
Regarding the sport known as American football, some people are such rabid fans that they can tell you the statistics of every p...

22 days ago

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Calculate FFT
Calculate the fft manually, without using matlab's builtin function. No cheating allowed.

23 days ago

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Fast Fourier transform algorithm
Your task is to implement the Fast Fourier transform algorithm, without using builtin MATLAB fft commands e.g. fft, fft2, or har...

23 days ago

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Solve an ODE: concentrations predicted by the cells-in-series model
One approach for predicting mixing and transport of contaminants in a river is the cells-in-series model. The model divides a ri...

24 days ago

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Local Extrema
Given a 2D (m,n>1) matrix, replace an element if it is not a local extrema (minima/maxima), with 0 (zero). Check the 3 neighbou...

24 days ago

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From sorted to original
Given a soted list (vector) and the indexes list., how can we retrieve the original one. Example: The sorted is: sv=[-1 0 2 5...

28 days ago

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Flip the right coin to survive!
Write a function to solve the problem mentioned below. The chessboard 8x8 matrix will be filled with coins randomly and given to...

29 days ago

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Weird Diagonal Matrix!!
Given an integer n, create a matrix whose diagonal elements will be square matrices of size 1 to n. For example: n=2 z = ...

29 days ago

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Compute the period of a pendulum started from a finite initial angle
Cody Problem 49830 asks for the period of a pendulum swinging through a small angle. Here the pendulum started at rest from an ...

30 days ago

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Leyland Primes
A Leyland Number is defined as a number of the form - x^y + y^x, or, x^y - y^x (x,y)>1 Given an array of numbers(>1), check...

30 days ago

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Draw a Diamond shape in ones Matrix with '0' s
Input will be odd numbers.The task is to make a Diamond shape in a ones matrix with '0's where the matrix will be a square matri...

1 month ago

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Solve an ODE: precocious pair’s porcine pursuit
In our previous encounters with Matilda and Labrun, the scintillating siblings collected candy wrappers, amused others with card...

1 month ago

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Spell musical triads
Chords form the basis of harmony in music. The most basic chords are triads, or groups of three notes. They are specified by thr...

1 month ago

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Matrix Transposition
Given a matrix and an index, perform matrix transposition as follows - Replace non-corner value of ith ring from outside, with...

1 month ago

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Determine whether a number is practical
A number is practical if all smaller numbers can be written as a sum of the proper divisors of . The number 24 is practical bec...

1 month ago

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Define an arithmetic sequence
Given three numbers n, a, and d, define an arithmetic sequence of n terms with a being the initial term of the sequence and d be...

1 month ago

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fractal circles
Create a fractal with circles using the same process as the Sierpinski triangle (https://en.wikipedia.org/wiki/Sierpinski_trian...

1 month ago

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Generate the Figure-Figure sequence
After discussing Scott Kim’s FIGURE-FIGURE Figure (below) in Gödel, Escher, Bach, Douglas Hofstadter introduced an integer seque...

1 month ago

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Find the slope of a line that passes through two vectors
Given two vectors p1 and p2, return the slope of a line that passes through p1 and p2. Examples: Input [p1,p2] = deal([0,1],[...

1 month ago

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Convert Cylindrical Cooridinates into Spherical Coordinate
For Cylindrical coordinate point, rho, fie (degrees) and z. Convert these points in Spherical Cooridinate System and save result...

2 months ago

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Count the Number of Directed Cycles in a Graph
Given an asymmetric adjacency matrix, determine the number of unique directed cycles. For example, the graph represented by adj...

2 months ago

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Factor Digits
Check if a given number in an array of numbers is - Equidigital Number - A number that has the same number of digits as the num...

2 months ago

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minimum numbers of 1 to build n
The (Mahler-Popken) complexity of n: minimal number of 1's required to build n using + and *. see A005245. In this problem, yo...

2 months ago

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Merge structs on fields
Merge a bunch of structs into one, containing the field names and corresponding values of all input structs. For duplicate field...

2 months ago

William

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