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Find the numeric mean of the prime numbers in a matrix.
There will always be at least one prime in the matrix. Example: Input in = [ 8 3 5 9 ] Output out is 4...

11 years ago

Solved

Sum the entries of each column of a matrix which satisfy a logical condition.
Given a numeric matrix A and a logical array L of the same size as A, return a row vector S containing the columnwise sums of th...

11 years ago

Solved

Cell joiner
You are given a cell array of strings and a string delimiter. You need to produce one string which is composed of each string fr...

11 years ago

Solved

Back to basics 9 - Indexed References
Covering some basic topics I haven't seen elsewhere on Cody. Given an input matrix and row and column, output the index of th...

11 years ago

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Sum all integers from 1 to 2^n
Given the number x, y must be the summation of all integers from 1 to 2^x. For instance if x=2 then y must be 1+2+3+4=10.

11 years ago

Solved

Replace all zeros and NaNs in a matrix with the string 'error'
Given a numeric input matrix A, possibly containing some zero values and some NaNs, replace any occurrences of zero or NaN with ...

11 years ago

Solved

Replicate elements in vectors
Replicate each element of a row vector (with NaN) a constant number of times. Examples : n=2, A=[1 2 3] -> [1 1 2 2 3 3] n=0...

11 years ago

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Right and wrong
Given a vector of lengths [a b c], determines whether a triangle with those sides lengths is a right triangle: <http://en.wikipe...

12 years ago

Solved

Multiply 2 numbers
Very easy, you just have to multiply 2 numbers but you cannot use the following signs (*, /, - ,^) ,mtimes , times, cross, pro...

12 years ago

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Check if sorted
Check if sorted. Example: Input x = [1 2 0] Output y is 0

12 years ago

Solved

Reverse the vector
Reverse the vector elements. Example: Input x = [1,2,3,4,5,6,7,8,9] Output y = [9,8,7,6,5,4,3,2,1]

12 years ago

Solved

Remove the air bubbles
Given a matrix a, return a matrix b in which all the zeros have "bubbled" to the top. That is, any zeros in a given column shoul...

12 years ago

Solved

Pizza!
Given a circular pizza with radius _z_ and thickness _a_, return the pizza's volume. [ _z_ is first input argument.] Non-scor...

12 years ago

Solved

Is my wife right?
Regardless of input, output the string 'yes'.

12 years ago

Solved

Are all the three given point in the same line?
In this problem the input is the coordinate of the three points in a XY plane? P1(X1,Y1) P2(X2,Y2) P3(X3,Y3) how can...

12 years ago

Solved

Return the 3n+1 sequence for n
A Collatz sequence is the sequence where, for a given number n, the next number in the sequence is either n/2 if the number is e...

12 years ago

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Change a specific color in an image
The ability to change colors can be a useful tool in image processing. Given an m x n x 3 array (much like CData in images), fin...

12 years ago

Solved

Back and Forth Rows
Given a number n, create an n-by-n matrix in which the integers from 1 to n^2 wind back and forth along the rows as shown in the...

12 years ago

Solved

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)...

12 years ago

Solved

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...

12 years ago

Solved

Getting the indices from a matrice
Getting the indices from a matrice. Inspired by Problem 645. Getting the indices from a vector by the great Doug Hull. Given a...

12 years ago

Solved

Fill a zeros matrix
The aim is to fill an array of all zeros given a numerical value and the index of row and columns for this value. 3 Inputs: ...

12 years ago

Solved

Column Removal
Remove the nth column from input matrix A and return the resulting matrix in output B. So if A = [1 2 3; 4 5 6]; and ...

12 years ago

Solved

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...

12 years ago

Answered
total number of elements which are not zero
Hi, what about: B = sum(Percey~=0,2); Regards, W.

12 years ago | 0

| accepted

Problem

Index of neighbor pixel with steepest gradient
Unlike in various applications, where the gradient of a two dimensional matrix is calculated in x and y direction, the gradient ...

12 years ago | 2 | 23 solvers

Answered
How can I perform a comparison function (of surrounding pixels) on a DEM using a starting pixel?
Hi, you might be interested in using the function ixneighbors available on the FEX which might make life a little easier for ...

12 years ago | 0

Solved

Bullseye Matrix
Given n (always odd), return output a that has concentric rings of the numbers 1 through (n+1)/2 around the center point. Exampl...

12 years ago

Solved

Select every other element of a vector
Write a function which returns every other element of the vector passed in. That is, it returns the all odd-numbered elements, s...

12 years ago

Solved

Compute the dilation of a binary image
A basic operation in image analysis is the dilation. Given an image where each pixel is either on or off (black/white, true/fals...

12 years ago