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Stefan Wehmeier

MathWorks

2011 年からアクティブ

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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 3
  • Knowledgeable Level 2
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How to stop MATLAB livescript from simplifying the answer?
Use sympref('AbbreviateOutput', false)

7年弱 前 | 3

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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 ...

約7年 前 | 0

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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...

7年以上 前 | 0

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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'))

7年以上 前 | 1

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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...

7年以上 前 | 1

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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 ...

8年弱 前 | 0

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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...

9年以上 前 | 0

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

9年以上 前 | 2

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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...

10年以上 前 | 0

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

10年以上 前 | 0

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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...

10年以上 前 | 0

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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...

10年以上 前 | 0

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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...

10年以上 前 | 0

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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...

10年以上 前

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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...

10年以上 前

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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.

10年以上 前

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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...

10年以上 前

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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 =...

10年以上 前

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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 ...

10年以上 前

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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...

10年以上 前

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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 ...

10年以上 前

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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...

10年以上 前

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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 = ...

10年以上 前

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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...

10年以上 前

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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 ...

10年以上 前

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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 + ...

10年以上 前

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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...

10年以上 前

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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...

10年以上 前

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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...

10年以上 前

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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 ...

10年以上 前

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