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William

Last seen: 1 day ago Active since 2012

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

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The perimeter of a circle
Calculate the perimeter of a circle E.g If input r(radius) = 2 , the output( the perimeter of a circle) = 12.5664.

3 days ago

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Easy Sequences 18: Set Bits of Triple Summations
The function S(n) is defined by the following triple summations: The double brackets mean that th...

4 days ago

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Free points!
Products of all elements in x. eg. x = [1 2 3 4 5]; y = 120;

4 days ago

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Easy Sequences 16: Volume of Embedded Octahedron
An octahedron (not regular) is formed by joining the centers of the faces of a rectangular parallelepiped (see below figure). ...

5 days ago

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Easy Sequences 15: Pythagorean Area with maximum Hypotenuse
A pythagorean triangle is defined as a right triangle with all three sides having integer lengths. Examples of pythogorean trian...

6 days ago

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Easy Sequences 13: Average Speed of Spaceship
A certain alien spaceship is capable of traveling at extremely high velocities and is able to change speed instantaneously. The ...

8 days ago

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Number of bytes required to store a sparse matrix
The input is always a sparse matrix : x = sparse(100,1000,0.01); >>whos x shows that 8024 bytes ares required . The a...

8 days ago

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Count the primes in Collatz sequences
Several Cody problems (21, 69, 42937, 44448, 44784, 52422) involve Collatz sequences. These start with a seed . If is odd, the ...

9 days ago

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List the Moran numbers
The quotient of a Moran number and its digit sum is prime. For example, 117 and 481 are Moran numbers because 117/(1+1+7) is 13 ...

9 days ago

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Convert a cell-array of values to MATLAB source code
The MATLAB interpreter loads your code and executes it using the Read-Evaluate-Print-Loop (see REPL). In this problem you will ...

12 days ago

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Modify subscripts
MATLAB supports object-oriented programming. Let's take an advantage of it in cody. This problem starts <http://uk.mathworks....

12 days ago

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List modest numbers up to n
After determining the nude numbers, or the numbers that openly display some of their divisors as their digits, one would think t...

16 days ago

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Count the ways to draw non-intersecting chords between points on a circle
There are 9 ways to draw non-intersecting chords between four points on the perimeter of a circle (including no chords at all). ...

17 days ago

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Determine whether a number is unprimeable
The number 204 is unprimeable because no single digit can be changed to make it prime. In contrast, the number 207 is not unprim...

18 days ago

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Determine whether a number is a fibodiv number
The number 14 is a fibodiv number because you can divide it into 1 and 4, use those numbers as the seeds for a Fibonacci sequenc...

19 days ago

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Borderline Connectivity
Compute the connected components of pixel borders. Suppose that h and v together describe a logical labeling of the borders b...

19 days ago

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Find the nth nude number
The number 672 is a nude number because it openly displays three of its divisors: 6, 7, and 2. In other words, a nude number is ...

21 days ago

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Metamorphosis
Inspired by problem <http://www.mathworks.com/matlabcentral/cody/problems/866-community-problem-500 866>. Can you make your c...

22 days ago

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Easy Sequences 11: Factorial Digits without Trailing Zeros
Here is an easy one... It is not difficult to count the number of digits of the factorial of a given number. For example for 'n...

23 days ago

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Easy Sequences 10: Sum of Cumsums of Fibonacci Sequence
The function F(n) is defined as the set of Fibonacci numbers from the first up to the n-th. S(n) is the result of applying to F,...

24 days ago

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Easy Sequences 9: Faithful Pairs
A "faithful number" is a non-prime number that is one less or one more than some prime number but not both. For example, for num...

25 days ago

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Circular Segment Area
Let us consider a circle with radius . If we draw an angle (in radians) from the center of the circle, the two radii forming th...

25 days ago

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Easy Sequences 8: Triangles with integer sides and prime perimeters
The triangle below is special. It has integer sides and a prime perimeter. Given an integer "n" we want to know how many t...

25 days ago

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Easy Sequences 6: Coefficient sums of derivatives
Consider the polynomial function and its first-order derivative . The sums of the coefficients of P and P', are and , respecti...

29 days ago

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Easy Sequences 5: Project Euler Problem 1 - Again!
We are all familiar with Project Euler Problem 1. This time let's try it on bigger multiples and larger range. Find the sum of ...

1 month ago

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Project Euler: Problem 1, Multiples of 3 and 5
If we list all the natural numbers below 10 that are multiples of 3 or 5, we get 3, 5, 6 and 9. The sum of these multiples is 23...

1 month ago

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Easy Sequences 4: Eliminate the Days of Confusion
If a date is written in purely numeric format some dates can be confusing, if we don't know the date format used. For example, "...

1 month ago

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Easy Sequences 3: Prime 44-number Squares
The positive integers 62 and 238 are related. Their squares (3844 and 56,644) both end in '44'. In fact, 62 and 238 are the 3rd ...

1 month ago

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Easy Sequences 2: Trigonometric function with integral input and output
The function 'F', defined as: , will always return an integer if the input is a natural number (in radian...

1 month ago