Community Profile

# Matt J

##### Last seen: Today
6,382 total contributions since 2009

Professional Interests: medical image processing, optimization algorithms

View details...

Contributions in
View by

How do I minimize this code
A=input('Enter Matrix A: ') B=input('Enter Matrix B: ') C=input('Enter Matrix C: ') n=length(A); Con=cell(1,n); Obs=Con....

8 hours ago | 0

x for y is?
[pks,idx] = findpeaks (-M2B{:,3},'MinPeakProminence',4); pks = -pks; peak_time=M2B{idx,1}; peak_displacement=M2B{idx,2};

19 hours ago | 0

| accepted

Array indices must be positive integers or logicsal values
The intention of this part of the code is unclear k=0; step=1; for q=0:step:6283 k=k+1; x(k)=q; y(k)=Ey(q); en...

20 hours ago | 0

Difference between Matrix and array?
Matrices can only be two-dimensional, whereas arrays can have any number of dimensions. The term "page" for the 3rd dimension do...

1 day ago | 0

| accepted

Problem related to fminbnd
You could plot the function to see how its shape varies with the parameters and to confirm whether fminbnd is giving the correct...

1 day ago | 0

| accepted

Visualizing 3 dimensional array
You could probably use volumeViewer, https://www.mathworks.com/help/images/explore-3-d-volumetric-data-with-volume-viewer-app.h...

2 days ago | 1

Calculate mean of every 4 elements in a row for an array

3 days ago | 0

Using if and of two columns to find the value in another column
Here, I use T as the name of your table, lookup=abs(T.X-78.5)<=0.5 & abs(T.Y-48.5)<=0.5; T.Value(lookup),

3 days ago | 0

| accepted

Same number of Rows and Cols of a matrix (N*N)
validateattributes(A,"numeric",{"square"})

4 days ago | 0

Constrained Global Optimization Problem with MultiStart, GA and HybridFunction using Parallel Processing whithout Step
A=input('Enter Matrix A: ') B=input('Enter Matrix B: ') C=input('Enter Matrix C: ') n=length(A); Con=cell(1,n); Obs=Co...

4 days ago | 0

How to do a matrix from vectors
One way, A=cell2mat( cellfun(@single,{time1 time2 Hs_buoy Tm_buoy Dm_buoy},'uni',0) )

4 days ago | 0

how can i split a 400*400 matrix into smaller one
You could do it as below, with the help of mat2tiles, https://www.mathworks.com/matlabcentral/fileexchange/35085-mat2tiles-div...

4 days ago | 0

Custom CUDA kernels and gpuArrays
Have a look at the documentation for CUDAKernel objects https://www.mathworks.com/help/parallel-computing/run-cuda-or-ptx-code-...

6 days ago | 1

| accepted

Redistribution of elements of various arrays into a single multidimensional one
I think the loop you've shown would work just fine, but a quicker way would be array2=repelem(reshape(array1,1,1,[]), 200,4);...

6 days ago | 1

discrte to softmax : Attempt to grow array along ambiguous dimension
I know its caused becouse target is larger then array but please help how i should change my code to make it work Did you inten...

6 days ago | 0

| accepted

Max of vector in higher dimensional array subject to constraints
N=ndims(A); %A is the given matrix z=size(A,N); idx=reshape(1:z, [ones(1,N-1),z] ) < constraint; %requires R2016b or h...

6 days ago | 1

| accepted

How to generate random integer from 1 to N except some integers in between?
No loops required, N=10; b=3; M=5; %example data list=setdiff(1:N,b); selection=list(randperm(N-1,M)) %result

6 days ago | 1

| accepted

Matrix consisting of sub-elements of another matrix
By indexing,e.g., >> x = [ 1 2 3 4 5 6 7 8 9]*10; >> y=x([1,2,4,5,9]) y = 10 20 40 50 90

6 days ago | 0

| accepted

How to create an object using class name
function newObj = createNewObject(obj) newObj = feval( class(obj) ); end

7 days ago | 0

| accepted

Adding just one line in my code slows the GPU.
Pre-allocate on the GPU. Also, pre-compute things on the GPU that are easily vectorized and don't depend on r. R=gpuArray.zeros...

7 days ago | 0

Converting a row to diagonal matrix
Did some guessing as to what you meant, but I think this is what you want: A=tril(true(16),-1); B=double(A); B(A)=rowdata; ...

7 days ago | 0

| accepted

Find minimum of a 15x100 and return in a vector of 1x100. is this possible?
The names of the variables you wrote to the table Min_AS,Med_AS,Max_AS are different from the original variable names you show...

7 days ago | 0

Solve equations in a loop with fsolve
Your equations are quadratic and therefore generally have two solutions, s. Fsolve cannot find them both for you. Why aren't you...

7 days ago | 0

| accepted

Any idea how to do and represent ttest results on box plot?
Usually, I just overlay them in powerpoint. But if you must automate this, one not too difficult way would be to use the line co...

8 days ago | 0

changing a group of numbers in a vector
As an example, >> cycles=[0,1,0,1,0,1]; %3 cycles >> A=repelem(cycles,3) A = Columns 1 through 16 0 0 ...

9 days ago | 0

How to replace a vector element with a value not equal the other vector values?
function sudokuRow = fillSudokuRow(sudokuRow) idx=(sudokuRow==0); sudokuRow(idx)=func(sudokuRow(~idx)); end

9 days ago | 0

Passing parameter values found in lsqcurvefit to be initial values for parameter estimation in another function
Some possibilities, Combine the code from both fitting steps into a single script. That way you will have direct access to the ...

9 days ago | 0

| accepted

Question

Is there a danger in renaming a Matlab install folder
I have Matlab R2019b installed under Windows 10 in the usual place, C:\Program Files\MATLAB\R2019b but I would now like to ren...

10 days ago | 2 answers | 1

### 2

Speeding up nested for-loops when vectorization seems to fail
Getting rid of repmat (requires R2016b or later) and working with single float precision will get you some speed-up. In doubles...

11 days ago | 0

| accepted