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Kaprekar numbers
Test if the input is a Kaprekar number: <http://mathworld.wolfram.com/KaprekarNumber.html>. Return a logical true or false. ...

14 years ago

Solved

Woodall number
Test whether the input is a Woodall number: <http://en.wikipedia.org/wiki/Woodall_number> _Please do not cheat by simply chec...

14 years ago

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Project Euler: Problem 8, Find largest product in a large string of numbers
Find the greatest product of five consecutive digits in an n-digit number. 73167176531330624919225119674426574742355349194934...

14 years ago

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vectorization in N
For a given integer n (n>1), compute the sum f (i) (1 <= i <= n) where f (i) = 1 if n is odd and 2 otherwise.

14 years ago

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Infernal Recursion
Consider the recursion relation: x_n = (x_(n-1)*x_(n-2))^k Given x_1, x_2, and k, x_n can be found by this definition. Wr...

14 years ago

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The Tower of Hanoi
In the <http://en.wikipedia.org/wiki/Tower_of_Hanoi Tower of Hanoi problem> with 3 rods (1, 2 & 3), the goal is to move a tower ...

14 years ago

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Construct a string from letters and counts
Given two input arrays like this: [5,3,1] ['a','b','c'] Output a string that contains each letter the specified num...

14 years ago

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fly fly away
A fly moves following a predefined sequence of discrete jumps (defined by the vectors _dx_ and _dy_) repeating the same sequence...

14 years ago

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Sorted highest to lowest?
Return 1 if the input is sorted from highest to lowest, 0 if not. Example: 1:7 -> 0 [7 5 2] -> 1

14 years ago

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Convert Roman to Arabic Numerals
Based upon what I see on tv and at the movies, the use of Roman numerals indicates something is important or sophisticated (e.g....

14 years ago

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Extract leading non-zero digit
<http://en.wikipedia.org/wiki/Benford%27s_law Benford's Law> states that the distribution of leading digits is not random. This...

14 years ago

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Summing digits
Given n, find the sum of the digits that make up 2^n. Example: Input n = 7 Output b = 11 since 2^7 = 128, and 1 + ...

14 years ago

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Circle and Quadratic
Imagine the quadratic curve with equation y=y(x)=ax^2+bx+c On the concave side of this curve there is a circle of radius...

14 years ago

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Math with Roman Numerals
Given a function R within (+,-,*,/) and two Roman numerals a & b, compute aRb in Roman numerals.

14 years ago

Solved

Swap the input arguments
Write a two-input, two-output function that swaps its two input arguments. For example: [q,r] = swap(5,10) returns q = ...

14 years ago

Solved

Find Rotated Substring
Given a string s1, find if a rotated version of s1 is present in a second string s2. For example, rotated version of some str...

14 years ago

Solved

Project Euler: Problem 5, Smallest multiple
2520 is the smallest number that can be divided by each of the numbers from 1 to 10 without any remainder. What is the smalle...

14 years ago

Solved

the fly, the train, the second train, and their Zeno's paradox
*You have heard this one*: A train leaves station _A_ and travels with constant velocity _v1_. A second train leaves station _B_...

14 years ago

Solved

Renaming a field in a structure array
MATLAB has a <http://www.mathworks.com/help/techdoc/ref/setfield.html setfield> and a <http://www.mathworks.com/help/techdoc/ref...

14 years ago

Solved

Read a Soroban Abacus
*Description* The Soroban is the name of the modern Japanese abacus. Information on reading a Soroban can be found <http://we...

14 years ago

Solved

Project Euler: Problem 16, Sums of Digits of Powers of Two
2^15 = 32768 and the sum of its digits is 3 + 2 + 7 + 6 + 8 = 26. What is the sum of the digits of the number 2^N? Thanks ...

14 years ago

Solved

Twins in a Window
<http://en.wikipedia.org/wiki/Twin_primes Twin primes> are prime numbers that differ by 2, such as [11,13] or [41,43]. Write a f...

14 years ago

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Smallest distance between a point and a rectangle
Given two points *x* and *y* placed at opposite corners of a rectangle, find the minimal euclidean distance between another poin...

14 years ago

Solved

Project Euler: Problem 9, Pythagorean numbers
A Pythagorean triplet is a set of three natural numbers, a b c, for which, a^2 + b^2 = c^2 For example, 3^2 + 4^2 =...

14 years ago

Solved

Project Euler: Problem 2, Sum of even Fibonacci
Each new term in the Fibonacci sequence is generated by adding the previous two terms. By starting with 1 and 2, the first 10 te...

14 years ago

Solved

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...

14 years ago

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Recurrence relation
A recurrence relation is given by P(1) := 1 P(n+1) := exp(1) - (n+1)*P(n) Write a function that, given an integer |...

14 years ago

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inner product of two vectors
inner product of two vectors

14 years ago

Solved

Return a list sorted by number of occurrences
Given a vector x, return a vector y of the unique values in x sorted by the number of occurrences in x. Ties are resolved by a ...

14 years ago

Solved

Great Circle Distance
Find shortest between two points on a ball given their azimuthal and polar angles (in degrees) as well as the radius of the sphe...

14 years ago