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# Jonathan

29 total contributions since 2013

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How can I do matrix multiplication on sets of data in an array without looping?
I don't know if it would be any more efficient than your loop (you could check with some timing tests) but here is an alternativ...

plotting fitted curve to a set of data
Here is some example code that shows two typical ways of plotting a data set a long with a fitted curve. % example plotting x,...

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I want to solve the equation within the loop and plot it, but it seems not work
Maybe you can explain further what you mean by it doesn't seem to work. What is it doing that you don't want it to do or what i...

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Issue with "Matrix Dimensions Must Agree"
With the dimensions you indicate, it seems that the denominator will have 12 elements (you say r is 1 x 12) and the denominator ...

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Find index of a matrix of values into another matrix
This should work assuming you have exactly one match in each row. If some rows have no matches or more than one match you will h...

Determining maximum and minimum Daily temperatures
If you have exactly 24 data points for each day (one for every hour) then you could use this approach, assume you have your data...

How to resolve an error for undefined function or variable 'x' within a function?
Without having the actual datafile that the program operates it is difficult to fully debug your code. A cursory inspection indi...

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How to make some optimization variables equal to each other?
I assume you are using one of the MATLAB optimization functions such as fmincon or linprog. These functions include arguments Ae...

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Repeat the concatenation of every n rows
I think this should do what you want: s = reshape(data',178*23,500)' Note the use of the transpose (accent symbol) first to tr...

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Sum Numbers Excluding Zeros
The following code should do what you want. There may be some way to do this more elegantly, but I think this works and should b...

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how can I generate a random angle?
Use randn or rand depending upon whether you want the angles to be normally distributed or uniformly distributed. Since randn ...

You haven't provided enough detail to answer your question too specifically but in general the steps would be to read the indivi...

How to optimize a vector, where only two values are allowed?
If your objective function is linear (I can't tell from what you have included) e.g. minimize over x, f'x where f is row vecto...

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MATLAB plot not showing.
The problem is that the second plot is replacing (overwriting) the first one in the figure window. If you open up a new figure, ...

How to find the location of the first string matching my searching criteria?
Assuming you can get a cell array B of character vectors containing the headers, and the strings you want to match assigned to s...

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Multiply each column of a matrix by another matrix
If I understand your question correctly then the result of the "operation for each column of E" will be on the main diagonal of ...

Plotting Root Locus with Pole/Zero Locations
Think about what a root locus plot actually is. It plots the locations of the roots (pole locations) in the complex plane as a f...

ungefär ett år ago | 0

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Dear Sirs, would you please help me and tell me how can I plot the average value of the previous y, while we have thousands (x, y) versus the current X?
If you do not want to keep all of the y's in memory and are only interested in the average of all of the y's up to the current s...

ungefär ett år ago | 0

How to solve the error?
Look closely at your your assignment statement, Block(l,k)=L0(i:i+b-1,j:j+b-1). The left hand side, Block(l,k) is a scalar value...

ungefär ett år ago | 0

Delete rows of table through search
I'm not sure from your description exactly what you are trying to do, but I assume it is one of the following two use cases. Use...

ungefär ett år ago | 0

Matrix manupulation to get specific index
You can use the MATLAB find function for this. For example: % Define your matrix A = [1 1 1;1 9 1;0 1 0]; % use f...

ungefär ett år ago | 0

"Inputs must be scalars" error message whilst using linspace command
your last line of code should be a =linspace(min(A(:,2)), max(A(:,2)),30); you had a colon separating min(A(:,2)) and m...

ungefär ett år ago | 0

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convert vector of n or any size into a matrix
Here's one way to do this. Note that I changed your notation to use n (rather than x) for the number of columns as this seems m...

mer än ett år ago | 0

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Time alignment of two signal with same length
I think the fundamental problem you have with your approach is not that the signals are the same length it is that they contain ...

mer än ett år ago | 0

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Question

How to prevent user from changing directory using uiputfile
I would like to allow a user to select a name for a file to be saved using a standard dialog box for saving files, such as uiput...

mer än 5 år ago | 3 answers | 0

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You can use the dot product block (with the same vector wired to both inputs) followed by a square root. Both are under the Math...

ungefär 6 år ago | 2

How to write cell array into a csv file
You could do it as follows with fprintf c = {'abc' 'def' 'ghk';[23],[24],[67];[87],[13],[999];[656],[6767],[546]}; fi...

ungefär 6 år ago | 3

Question

How can I construct a dataset array from data on an excel worksheet with an unknown number of rows
I would like to construct a dataset array from data on an Excel worksheet. I know the location of the upper left corner of the ...

ungefär 6 år ago | 2 answers | 0