Community Profile

# Bobby Cheng

### MathWorks

51 total contributions since 2012

View details...

Contributions in
View by

Is there a big error in the method matlab uses to finds sqrtm?
This is an interesting example. It goes to the heart of the issue when computes with floating point arithmetic. First consider t...

mehr als 4 Jahre ago | 3

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]

fast 8 Jahre ago

Solved

Make one big string out of two smaller strings
If you have two small strings, like 'a' and 'b', return them put together like 'ab'. 'a' and 'b' => 'ab' For extra ...

fast 8 Jahre ago

Solved

Is my wife right? Now with even more wrong husband
Again, as in "Is my wife right?" ( <http://www.mathworks.com/matlabcentral/cody/problems/149-is-my-wife-right> ), answer 'yes' r...

fast 8 Jahre ago

Solved

Magic!
Check whether the input matrix is a normal magic square: <http://en.wikipedia.org/wiki/Magic_square> Output the logical va...

fast 8 Jahre ago

Solved

The Hitchhiker's Guide to MATLAB
Output logical "true" if the input is the answer to life, the universe and everything. Otherwise, output logical "false".

fast 8 Jahre ago

Solved

inner product of two vectors
inner product of two vectors

fast 8 Jahre ago

Solved

Program an exclusive OR operation with logical operators
Program an exclusive or operation *without* using the MATLAB function xor. Use logical operators like |, &, ~, ... instead. ...

fast 8 Jahre ago

Solved

Too mean-spirited
Find the mean of each consecutive pair of numbers in the input row vector. For example, x=[1 2 3] ----> y = [1.5 2.5] x=[1...

fast 8 Jahre 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...

fast 8 Jahre ago

Solved

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

fast 8 Jahre ago

Solved

Function Iterator
Given a handle fh to a function which takes a scalar input and returns a scalar output and an integer n >= 1, return a handle f...

fast 8 Jahre ago

Solved

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

fast 8 Jahre ago

Solved

Trimming Spaces
Given a string, remove all leading and trailing spaces (where space is defined as ASCII 32). Input a = ' singular value deco...

fast 8 Jahre 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...

fast 8 Jahre ago

Solved

How to find the position of an element in a vector without using the find function
Write a function posX=findPosition(x,y) where x is a vector and y is the number that you are searching for. Examples: fin...

fast 8 Jahre ago

Solved

Sums with Excluded Digits
Add all the integers from 1 to n in which the digit m does not appear. m will always be a single digit integer from 0 to 9. no...

fast 8 Jahre ago

Solved

Target sorting
Sort the given list of numbers |a| according to how far away each element is from the target value |t|. The result should return...

fast 8 Jahre ago

Solved

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 + ...

fast 8 Jahre ago

Solved

Pascal's Triangle
Given an integer n >= 0, generate the length n+1 row vector representing the n-th row of <http://en.wikipedia.org/wiki/Pascals_t...

fast 8 Jahre ago

Solved

Replace NaNs with the number that appears to its left in the row.
Replace NaNs with the number that appears to its left in the row. If there are more than one consecutive NaNs, they should all ...

fast 8 Jahre ago

Solved

Binary numbers
Given a positive, scalar integer n, create a (2^n)-by-n double-precision matrix containing the binary numbers from 0 through 2^n...

fast 8 Jahre ago

Solved

Weighted average
Given two lists of numbers, determine the weighted average. Example [1 2 3] and [10 15 20] should result in 33.333...

fast 8 Jahre ago

Solved

Create times-tables
At one time or another, we all had to memorize boring times tables. 5 times 5 is 25. 5 times 6 is 30. 12 times 12 is way more th...

fast 8 Jahre 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 ...

fast 8 Jahre ago

Solved

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

fast 8 Jahre ago

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...

fast 8 Jahre ago

Solved

Nearest Numbers
Given a row vector of numbers, find the indices of the two nearest numbers. Examples: [index1 index2] = nearestNumbers([2 5 3...

fast 8 Jahre ago

Solved

Most nonzero elements in row
Given the matrix a, return the index r of the row with the most nonzero elements. Assume there will always be exactly one row th...

fast 8 Jahre ago

Solved

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...

fast 8 Jahre ago