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# Goncalo Costa

Last seen: 5 days ago Active since 2021

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Question

How can I convert a contour to a binary matrix?
I have the contour of a 3D surface at different levels and I have extracted its coordinates (for each level). I want to then con...

1 month ago | 1 answer | 0

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Question

How do I obtain the area of each contour on a contour3 plot?
I have written a code that overlaps a 3D scan with some external data from the object being analysed, resulting in a plot simila...

1 month ago | 1 answer | 0

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Question

How do I find the minimum between a matrix and a varying matrix function? I get "Error in fmincon (line 563) initVals.f = feval(funfcn{3},X,varargin{:});"
I am trying to analyse how close, percentually, my samples are to pure water (0%) and to "no water"/dried (100%). In theory my r...

5 months ago | 1 answer | 0

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Question

Why does solving my equation result in the message "No complex subexpressions allowed in real mode."?
I have an equation with a bunch of complex values in it, and with a variable in it that experimentally must be a real number. I ...

7 months ago | 2 answers | 0

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Question

Why does my colour bar not go up to the maximum values in the matrix?
I am imaging a matrix A with the following code: I = imgaussfilt(A,2); I2 = imsharpen(I); I3 = imresize(I2, 5); figure(3), i...

8 months ago | 1 answer | 0

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Question

How can identify the incorrect data array from a graph?
I have a bunch of (30) data arrays (they are all 1 x 2218 arrays) and I have plotted them to show something like this: In thes...

10 months ago | 1 answer | 0

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Question

How to get specific tick axis values equally spaced, independently of their values?
I have got the following code to create a 2D colour map of the quantity ref_n_order , depending on the Frequency and on the Soli...

12 months ago | 2 answers | 0

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Question

How to filter noise in a 3D structure/data array?
I have a 3D structure of a water droplet (from an .asc file), this water droplet could be seen with a naked eye (approximately 2...

1 year ago | 1 answer | 0

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Question

How do I crop a matrix within desired numerical limits?
I have a 3D matrix representing an image (related to another question on the website), but I am only truly interested in a small...

1 year ago | 2 answers | 0

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Question

How to accurately measure the height of a 3D structure?
I have a 3D data array consisting of a scan of a semi-circular sample on a flat surface. The purpose of this is to image and aft...

1 year ago | 1 answer | 0

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How to iterate through the struct char to label a new struct correctly?
I ended up solving it and I am placing here my answer: % List of all the desired files in the folder filePattern = fullfil...

1 year ago | 0

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Question

How to iterate through the struct char to label a new struct correctly?
I know that when I create a structure, e.g. fruits(1).apples = data1; fruits(1).bananas = data2; I obtain a structure with tw...

1 year ago | 3 answers | 0

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Question

How to iterate over a char array and store them into a separate array?
I am developing a code that iterates over files with different names, and then processes the data of each file, one at a time. ...

1 year ago | 1 answer | 0

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Question

How do I delete a repeated element in a single array cell?
I am trying to applying a filter through an array of signals, but the filter must be aligned with the signal's peak (max value)....

1 year ago | 1 answer | 0

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Question

How do I correctly use vpasolve?
I am trying to numerically solve the following set of equations M_mag = 1 ; %just some con...

1 year ago | 2 answers | 0

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Question

How do I solve this set of equations using MATLAB?
I am trying to solve the following equations for the variable : and for that I wrote the following: sy...

1 year ago | 2 answers | 0

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Question

How do I do the fourier transform of a data array?
I have been trying to do the fourier transform of a reference signal and of a row of signals, but the results I am getting are n...

2 years ago | 1 answer | 0

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Question

Dot indexing is not supported for variables of this type. - trying to create a function to upload files matrices
I am trying to write a function that allows me to upload a chosen mat file and to take specific matrices from these files, so th...

2 years ago | 2 answers | 0

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Question

How to specify Hexadecimal Color Code on a fit line?
I have been able to present a fit line through a scatter plot by writting the following, in a for loop: t_array: time array P2...

2 years ago | 2 answers | 0

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Question

How to plot a biexponential fit?
I have got some data array (P2P) and a time array (t_array) plotted under this simple line of code: plot(t_array, P2P, 'o') Th...

2 years ago | 0 answers | 0

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Question

What differentiates h5 and mat files? How can I process the mat file's information?
A colleague has written a LabVIEW code that processes a time-domain signal and saves them as .mat files, but to analyse this dat...

2 years ago | 1 answer | 0

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Question

How to apply the limits to a plots created in a for loop? And how to make it faster?
I have a series of files that I got in 5 minutes intervals from each other, and I would like to plot all of them together in a s...

2 years ago | 0 answers | 0

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Question

How to delete more than one point from data array in loop?
I have written the following bit to avoid plotting a wrong measurement, from an array of measurements. For the 3 different data ...

2 years ago | 1 answer | 0

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Question

Why does my for loop cause MATLAB to not stop running?
The code I am writing has as its purpose to analyse some data and plot it accordingly. My data consists of a series of consecuti...

2 years ago | 1 answer | 0

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Question

How to create an array of matrices?
If I have 3 matrices: A = [1 2 ; 3 4] B = [5 6 ; 7 8] C = [9 10 ; 11 12] And I want to create a greater matrix with these in...

2 years ago | 3 answers | 0

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Question

How do I create a loop for an equation using if statements?
I want to define an equation/function, to later plot, that changes every cycle. If we consider each cycle to last for example ...

2 years ago | 1 answer | 0

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Question

How do I add values to specific values/ specific place of an already existing array?
I have an array of number, t , from which I have extracted some elements at even intervals (every 30 elements, one was extracted...

2 years ago | 1 answer | 0

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Question

How to open a file of unknown type?
I am trying to open a file "pulse" of type "file", on my MATLAB, with the purpose of plotting a 2D graph. The type of the file i...

2 years ago | 1 answer | 0

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Question

How to keep track of where each measurement originates from?
When creating a pattern/mask for single-pixel imaging of a picture, I use a different delta function for each measurement, and t...

3 years ago | 1 answer | 0