Community Profile # Bobby Cheng

Last seen: 9 jours ago Active since 2012

#### Statistics

All
• • • • • #### Content Feed

View by

Matlab is significantly slower than Julia on simple evaluation
First of all, thank you for creating the benchmark and raising this performance issue. Indeed, we are seeing more and more perfo...

9 mois ago | 11

| accepted

expm function problem for stiff matrix
This is a weakness of the scaling and squaring algorithm. Inside EXPM, which you can read the implementation, there are special ...

environ un an ago | 0

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...

presque 7 ans 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]

plus de 10 ans 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 ...

plus de 10 ans 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...

plus de 10 ans ago

Solved

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

plus de 10 ans 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".

plus de 10 ans ago

Solved

inner product of two vectors
inner product of two vectors

plus de 10 ans 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. ...

plus de 10 ans 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...

plus de 10 ans 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...

plus de 10 ans ago

Solved

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

plus de 10 ans 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...

plus de 10 ans ago

Solved

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

plus de 10 ans 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...

plus de 10 ans 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...

plus de 10 ans 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...

plus de 10 ans 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...

plus de 10 ans 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...

plus de 10 ans 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 + ...

plus de 10 ans 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...

plus de 10 ans 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 ...

plus de 10 ans 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...

plus de 10 ans 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...

plus de 10 ans 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...

plus de 10 ans 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 ...

plus de 10 ans ago

Solved

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

plus de 10 ans 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...

plus de 10 ans 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...

plus de 10 ans ago