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Getting logical indexes

This is a basic MATLAB operation. It is for instructional purposes. --- Logical indexing works like this. thresh = 4...

1 year ago

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Circumscribed circles

Given the lengths of the 3 sides of a triangle, output the radius of the circumscribed circle. Example: [3 4 5] -> 2.5

1 year ago

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Mandelbrot Numbers

The <http://en.wikipedia.org/wiki/Mandelbrot_set Mandelbrot Set> is built around a simple iterative equation. z(1) = c z...

1 year ago

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Project Euler: Problem 10, Sum of Primes

The sum of the primes below 10 is 2 + 3 + 5 + 7 = 17. Find the sum of all the primes below the input, N. Thank you <http:/...

1 year ago

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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 =...

1 year 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...

1 year ago

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Project Euler: Problem 6, Natural numbers, squares and sums.

The sum of the squares of the first ten natural numbers is, 1^2 + 2^2 + ... + 10^2 = 385 The square of the sum of the first ...

1 year ago

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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...

1 year ago

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Project Euler: Problem 4, Palindromic numbers

A palindromic number reads the same both ways. The largest palindrome made from the product of two 2-digit numbers is 9009 = 91 ...

1 year ago

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Project Euler: Problem 3, Largest prime factor

The prime factors of 13195 are 5, 7, 13 and 29. What is the largest prime factor of the number being input, input might be ui...

1 year ago

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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...

1 year 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 year ago

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Some Assembly Required

The input to this function is a matrix of real numbers. Your job is to assemble the rows of the matrix into one large row that ...

1 year ago

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Back to basics 23 - Triangular matrix

Covering some basic topics I haven't seen elsewhere on Cody. Given an input matrix, return a matrix with all elements above a...

1 year ago

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Matrix with different incremental runs

Given a vector of positive integers a = [ 3 2 4 ]; create the matrix where the *i* th column contains the vector *1:a(i)...

1 year ago

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Permute diagonal and antidiagonal

Permute diagonal and antidiagonal For example [1 2 3;4 5 6;7 8 9] -> [3 2 1;4 5 6;9 8 7] WITHOUT diag function (and variable n...

1 year ago

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Create logical matrix with a specific row and column sums

Given two numbers *|n|* and *|s|*, build an |n-by-n| logical matrix (of only zeros and ones), such that both the row sums and th...

1 year ago

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intersection of matrices

Given two matrices filled with ones and zeros, determine if they share a common row, column entry. These matrices are of identi...

1 year ago

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We love vectorized solutions. Problem 1 : remove the row average.

Given a 2-d matrix, remove the row average from each row. Your solution MUST be vectorized. The solution will be tested for ac...

1 year ago

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Set the array elements whose value is 13 to 0

Input A either an array or a vector (which can be empty) Output B will be the same size as A . All elements of A equal to 13...

1 year ago

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Find the largest value in the 3D matrix

Given a 3D matrix A, find the largest value. Example >> A = 1:9; >> A = reshape(A,[3 1 3]); >> islargest(A) a...

1 year ago

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Check if number exists in vector

Return 1 if number _a_ exists in vector _b_ otherwise return 0. a = 3; b = [1,2,4]; Returns 0. a = 3; b = [1,...

1 year ago

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Operate on matrices of unequal, yet similar, size

You may want to add a vector to a matrix, implying that the vector is added to each column of the matrix. Or multiply a 3x4x5 ma...

1 year ago

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Rotate input square matrix 90 degrees CCW without rot90

Rotate input matrix (which will be square) 90 degrees counter-clockwise without using rot90,flipud,fliplr, or flipdim (or eval)....

1 year ago

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Removing rows from a matrix is easy - but what about inserting rows?

Assume A is a 5-by-5 matrix. A([2,4],:) = [] is a quick way to remove rows 2 and 4. Can you find a quick way to insert rows into...

1 year ago

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Set some matrix elements to zero

First get the maximum of each *row*, and afterwards set all the other elements to zero. For example, this matrix: 1 2 3 ...

1 year ago

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N-Dimensional Array Slice

Given an N-dimensional array, _A_, an index, _I_, and a dimension, _d_, return the _I_ th elements of _A_ in the _d_ dimension. ...

1 year ago

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surrounded matrix

With a given matrix A (size m x n) create a matrix B (size m+2 x n+2) so that the matrix A is surrounded by ones: A = [1 2 ...

1 year ago

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Make an awesome ramp for a tiny motorcycle stuntman

Okay, given a vector, say v=[1 3 6 9 11], turn it into a matrix 'ramp' like so: m=[1 3 6 9 11; 3 6 9 11 0; 6 9 ...

1 year ago

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Reverse the elements of an array

Reverse the order of elements in an array: eg: input X = [ 1 2 3 ; 4 5 6 ; 7 8 9 ] o...

1 year ago