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How do I make a condition statement for an element that presents in two different arrays but is at the wrong position? This also applies to more than one elements
Assuming you have already made the check for the correct number in the correct spot, you can use this ismember(final_code_guess...

5 years ago | 0

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MATLAB determine if matrices are invertible or not
You can use rank( ) for this: https://www.mathworks.com/help/matlab/ref/rank.html?searchHighlight=rank&s_tid=srchtitle_rank_1 ...

5 years ago | 1

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Using Trapezodial rule Matlab
The trapezoid rule is for situations where you know the function values in advance, but you don't have this situation. I.e., if ...

5 years ago | 0

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fortran subroutine includes several other subroutines
Note that the timestwo.F example that comes with MATLAB is a bad example of Fortran code. It has several bugs in it that could l...

5 years ago | 3

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Call C/C++ Code from MATLAB Code
If your code includes a file called MyStruct.h, then yes you should have such a file. I would expect it to be something like th...

5 years ago | 0

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Matlab tries to use mex files not on search path
You should use debugging to find out why this is happening. Type the following at the command line: dbstop if error then run y...

5 years ago | 0

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MATLAB: failed creating a diagonal matrix
You probably have inadvertently created a variable named 'diag' in your workspace, and hence diag(x) is simply indexing into thi...

5 years ago | 0

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For-loops are now faster than some of the simplest vectorized statements. Why do we still need so much deep copying?
I have read rumors in the past that TMW was tinkering with the idea of sub-array references, or some type of limited pointer cap...

5 years ago | 1

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Answered
what correction is required in the code?
If the homework assignment specifies you must use a loop, then I don't think the intent was for you to wrap a simple i=1 range a...

5 years ago | 0

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I am trying to solve 3rd order ode by RK45, but I did not get solution and plot, kindly fix my issues
The image appears to show seven equations (H1', H2', ..., H7') with boundary conditions at 0 and infinity. The RK45 scheme you ...

5 years ago | 0

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If statement in loop with AND OR operands
The problem is that the comparison Outcome{j} == '11_right' is an array comparison, not a scalar comparison. I.e., the string i...

5 years ago | 0

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How to create a equally distributed batting order for little league baseball team
Start with a simple pattern that works, and then randperm both the rows and columns. E.g., B = zeros(10); for k=1:10 % start w...

5 years ago | 0

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Answered
Unable to perform assignment because the size of the left side is 1-by-1 and the size of the right side is 1-by-2
Does this do what you want: Xindex(r, :) = [index rowidx]; You can get rid of c altogether since it isn't needed. And you nee...

5 years ago | 1

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How do I store a string from a MATLAB structure into a C structure in a MEX file?
Please show us the definitions of the variables involved. How large is cstructu->Field1, cstructu->Field2, and cstructu->Field3?...

5 years ago | 0

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How to calculate sum(A .* (B * C), 'all') [Ed. actually sum(A .* log(B * C), 'all')] efficiently when A is sparse and B*C is full and large?
Here is the straightforward mex code (i.e., no parallel sections) if you want to try it out. It computes the result directly in...

5 years ago | 3

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Answered
what does the expression " if ( ) && ( ) " do
&& is the "logical and" operator. You can read about it here: https://www.mathworks.com/help/matlab/ref/logicaloperatorsshortc...

5 years ago | 0

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Answered
How to calculate sum(A .* (B * C), 'all') [Ed. actually sum(A .* log(B * C), 'all')] efficiently when A is sparse and B*C is full and large?
You could use this loop to avoid the memory usage, but it will run slowly because of the data copying going on in the background...

5 years ago | 0

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ODE system with 2 degrees of freedom
I only see two variables, 1 and 2, and each is part of a 2nd order equation. So that would mean a 2 x 2 = 4 element state vecto...

5 years ago | 0

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Answered
Extracting the sub-matrix
You might benefit from going through the onramp tutorials found here: https://matlabacademy.mathworks.com/details/matlab-onramp...

5 years ago | 1

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How can I solve these differential equations?
A general outline would be to create your derivative function as follows: function dy = myderivative(t,y,T,E) Fa = y(1); Fb =...

5 years ago | 0

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Exponent mantissa form of real numbers
Without seeing the actual wording of the assignment, I would assume this simply means "floating point notation". E.g., 123.456...

5 years ago | 1

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Matrix product using for/while loop
The inner most loop needs to iterate over the 2nd index of M1, not the first index. E.g., while (k<=size(M1,2)) %<-- 2nd inde...

5 years ago | 0

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What does 'li' mean?
1i is used to ensure it isn't confused with a variable named i that you might have in the workspace. I.e., 1i is always sqrt(-1...

5 years ago | 0

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I have matrix A and I need to find (e^(At)) where t is the sampling time. How to find that? Also what is the difference between exp(A) and expm(A)?
exp(A) just takes the exp( ) of the scalar elements individually. I.e., exp(A(1,1)), exp(A(1,2)), etc. expm(A) takes the matri...

5 years ago | 1

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help with my 4th order runge kutta code
My guess without seeing the rest of your code is that phi is a column vector, so when you add phi*h to the row vector Y(i,:) it ...

5 years ago | 0

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how to change from for loop to while loop
You never change i or Errors within the while loop, so how is the loop ever supposed to exit? Maybe you want to add this line: ...

5 years ago | 0

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Is mxCopyPtrToInteger4() not compatible with Interleaved Complex API ?
See this post: https://www.mathworks.com/matlabcentral/answers/93860-why-does-the-fortran-mex-api-function-mxcopyptrtointeger4-...

5 years ago | 0

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What should go in a next-generation MATLAB X?
Symmetric variables and Hermitian variables. MATLAB could implement bit flags in the mxArray header to indicate this and they c...

5 years ago | 0

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Why indexing vs not indexing the 2D matrix will lead to different result?
Some links related to this known behavior: https://www.mathworks.com/matlabcentral/answers/599818-computational-complexity-of-m...

5 years ago | 0

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Properly resizing mxCreateStructMatrix post-2018a?
TMW doesn't publish the complete rules for how the data areas of structs are organized, but historically they have always put ea...

5 years ago | 0