Community Profile # William

Last seen: Today Active since 2012

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

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circa 23 ore 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...

9 giorni 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 <<...

10 giorni 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...

10 giorni 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 ...

11 giorni 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...

12 giorni ago

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

13 giorni 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...

13 giorni 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...

14 giorni 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...

14 giorni 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...

18 giorni 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...

19 giorni 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 = ...

19 giorni 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 ...

20 giorni 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...

20 giorni 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...

21 giorni 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...

24 giorni ago

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

24 giorni 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...

circa un mese 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...

circa un mese 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...

circa un mese 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...

circa un mese 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...

circa un mese 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],[...

circa un mese 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...

circa un mese 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...

circa un mese 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...

circa un mese 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...

circa un mese 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...

circa un mese ago

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Find the particular dividend
It is known that once you write the sequence 10101...101 long enough, the number will be finally divisible by any odd number if ...

circa un mese ago