Community Profile # William

Last seen: 1일 전 2012 이후 활성

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

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1일 전

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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...

10일 전

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

11일 전

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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...

11일 전

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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 ...

12일 전

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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...

13일 전

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

14일 전

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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...

14일 전

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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...

15일 전

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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...

15일 전

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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...

19일 전

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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...

20일 전

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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 = ...

20일 전

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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 ...

20일 전

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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...

20일 전

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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...

22일 전

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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...

24일 전

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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...

25일 전

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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...

약 1달 전

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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...

약 1달 전

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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...

약 1달 전

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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...

약 1달 전

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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...

약 1달 전

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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],[...

약 1달 전

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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...

약 1달 전

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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...

약 1달 전

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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...

약 1달 전

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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...

약 1달 전

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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...

약 1달 전

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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 ...

약 1달 전