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Stefan Wehmeier

MathWorks

Attivo dal 2011

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Working on the symbolic toolbox, mostly in the MuPAD language. Responsible for solvers and simplifiers.
Professional Interests: computer algebra

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  • Knowledgeable Level 2
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Risposto
How to stop MATLAB livescript from simplifying the answer?
Use sympref('AbbreviateOutput', false)

quasi 7 anni fa | 3

| accettato

Risposto
These equations have an answer - how to get solve to find it?
Why not just solve(expression1 == expression2, u) ? What you did is to confuse assignemnts/assumptions with equations. You ...

quasi 7 anni fa | 0

Risposto
Function Iteration for n times, but n is NOT a fixed number
Why don't you make your last source code the body of a function? Is l at any time called with non-constant argument, such that y...

circa 7 anni fa | 0

Risposto
an error in new versions? triognometric function of A*t
It is a matter of taste if you prefer results in terms of exp or sin. You could do simplify(rewrite(A1, 'sin'))

oltre 7 anni fa | 1

| accettato

Risposto
Symbolic toolbox mpower unexpected behaviour
You can use symbolic N but not in connection with mpower. As T^N = exp(N*log(T)), write TN = expm(N*logm(T)) and procee...

oltre 7 anni fa | 1

| accettato

Risposto
mupad command calling from matlab produce wrong results
I cannot reproduce this. In any case, you cannot work with intervals in MATLAB; this is why poles(f) gives you just the ...

oltre 7 anni fa | 0

Risposto
Why does eig(A) not return a symbolic array for my symbolic matrix A?
The roots of polynomials of degree > 4 usually do not have a symbolic representation. The same holds for eigenvalues as they are...

oltre 9 anni fa | 0

| accettato

Risposto
Simplify expression with exponential function.
Use exp(sym(1))

oltre 9 anni fa | 2

| accettato

Risposto
Parametric solutions to system of equations inequations via solve()
I see that you are using R2014a. Then your only option is to solve for one variable solve(e(1) == 0, a) and take this as...

circa 10 anni fa | 0

| accettato

Risposto
subs(a,b,1) introduces variable b into a?
I cannot reproduce this. If it happens (in which version ??), then it is clearly unexpected.

circa 10 anni fa | 0

Risposto
Problems with matlab symbolic dsolve function
The correct syntax is syms y(x) dsolve(diff(y, x, x) +y==x*exp(-x^2)) as it declares y as a function of x (and not of...

circa 10 anni fa | 0

Risposto
Matlab 2012b too slow when solving a system of two equations on mupadmex(statement)
A running time of one hour can be normal if the equations are very complicated. Since your code does not run as it stands, it is...

circa 10 anni fa | 0

Risposto
Symbolic array pre-allocation
My question is in which form do you have the 50000 entries you want to fill in. As strings in a cell array A? Then B = cell...

circa 10 anni fa | 0

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Risolto


Return the first and last character of a string
Return the first and last character of a string, concatenated together. If there is only one character in the string, the functi...

circa 10 anni fa

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Make a Palindrome Number
Some numbers like 323 are palindromes. Other numbers like 124 are not. But look what happens when we add that number to a revers...

circa 10 anni fa

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Determine if input is odd
Given the input n, return true if n is odd or false if n is even.

circa 10 anni fa

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Which doors are open?
There are n doors in an alley. Initially they are all shut. You have been tasked to go down the alley n times, and open/shut the...

circa 10 anni fa

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De-dupe
Remove all the redundant elements in a vector, but keep the first occurrence of each value in its original location. So if a =...

circa 10 anni fa

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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 ...

circa 10 anni fa

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Who Has the Most Change?
You have a matrix for which each row is a person and the columns represent the number of quarters, nickels, dimes, and pennies t...

circa 10 anni fa

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Find the sum of all the numbers of the input vector
Find the sum of all the numbers of the input vector x. Examples: Input x = [1 2 3 5] Output y is 11 Input x ...

circa 10 anni fa

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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...

circa 10 anni fa

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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 = ...

circa 10 anni fa

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

circa 10 anni fa

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The Goldbach Conjecture
The <http://en.wikipedia.org/wiki/Goldbach's_conjecture Goldbach conjecture> asserts that every even integer greater than 2 can ...

circa 10 anni fa

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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 + ...

circa 10 anni fa

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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...

circa 10 anni fa

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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...

circa 10 anni fa

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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...

circa 10 anni fa

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Who knows the last digit of pi?
There is only one man who knows the last digit of pi, who is that man? Give the name of that man, who, by popular believe, can ...

circa 10 anni fa

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