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# Lu Da Silva

Last seen: 9 månader ago Active since 2020

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Question

How to select rows in a matrix based on the values in another matrix?
Hi, I have a matrix A and a matrix B: -------- A ------- ---------- B --------- 201918 4.5 ...

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Question

How to convert datetime into a number?
I have a table whose first column is a timestamp in the format 08-Jan-2016 05:40:00. How do I convert it into numbers? Wanted o...

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How to find 5 consecutive values above threshold within a certain window?
I have a vecor A: A = [6 7 8 8 8 7 6 7 6 2 7 8 9 3 3 4 6 7 8 9] The threshold is 5. I want to keep all values that are above t...

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How to export a table including column names?
I have a matrix A that I want to convert into a table with variable names and export as csv. This is my code: MyTable = array2...

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How to calculate R^2 based on external linear equation?
I have a scatter and I calculated the slope and intercept of the best fitting line (using orthogonal regression). So now I have...

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How to place values in a matrix with values from another matrix?
I have 2 tables A and B: A B 2018 13 2018 0.2 2019 15 2019 0.3 2020...

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How to specify max. number of outliers on which to apply the Hampel filter?
I have a timeseries with outliers. However, sometimes these occur consequtively, e.g. 20 datapoints one after the other. This po...

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How to solve two equations with two unknowns that are vectors?
I have to find 2 vectors x and y as follows: syms x y; E = [ws == sqrt(x^2+y^2), wd == atan2(x,y)]; S = vpasolve(E,x,y); ws ...

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Subtracting elements within a table
I have a table: 1 23 2 24 3 21 4 34 1 89 2 23.2 3 34.8 4 -23.1 and it c...

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How to keep rows whose values follow a certain sequence?
I have a matrix composed of two columns A and B, I need to only keep the rows which contain the sequence 90-180-270: A B ...

ungefär ett år ago | 2 answers | 0

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Question

How to convert all array values into negative ones?
I have an array A: A = [2; 3; 5; -8; 9; 1; -1] how do I convert it into an array whose values are all negative? So as to obtai...

ungefär ett år ago | 4 answers | 0

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How to apply this formula into a matlab loop?
Hi, I have a table that looks like this: % have: % wanted: X Y Z ___________________________...

ungefär ett år ago | 1 answer | 0

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How do I delete all rows in a table depending on one column's NaNs?
Hi, I have a table A: 1 2 3 NaN 4 5 3 4 NaN I need to delete all rows where column ...

ungefär ett år ago | 1 answer | 0

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How to solve an equation with a vector as unknown?
I solved it with this code: syms X eqn = M == X * sqrt((X-A)^2 + B^2); sol = arrayfun(@vpasolve,eqn,'uniform',0);

ungefär ett år ago | 0

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Question

How to solve an equation with a vector as unknown?
I have the following equation: M = X * sqrt((X-A)^2 + B^2) A and B are constants but M is a vector containing 100 values. I'm ...

ungefär ett år ago | 1 answer | 0

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Question

How to delete all rows of a matrix wherever any value is invalid (999)?
I have a matrix M of 100 rows and 4 colums. Whenever column 1 of M is 99 I want to delete the entire row. Also whenever column...

ungefär ett år ago | 3 answers | 0

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Question

How to retrieve the indices of the values in each bin?
I have a histogram with values from a vector A , spread into 30 bins. How can I get the indices of the values in A, that corresp...

mer än ett år ago | 1 answer | 0

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Question

How to create vectors out of (histogram) bins and take averages?
I have a vector containing speeds from 0.25m/s to 20m/s. I need to bin the speeds in bins of 0.5m/s widths cenetred at integers ...

mer än ett år ago | 1 answer | 0

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Question

How to find the intersection of a fitting line with a logarithmic y-axis?
I have a vector A = [10 40 60 80] and a vecor B = [5 6 7 8] I need to create a plot where the x-axis is B and the y-axis is A ...

mer än ett år ago | 1 answer | 0

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Question

Group values of a vector into new vectors according to magnitude
I have a vector A with different values of angles: A = [17 323 100 3 278 220 45 351 212 51] what I need is to group all angles...

mer än ett år ago | 2 answers | 0

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Question

How to set x-axis into HH:MM format?
I have a double of 21x1 which corresponds to the air temperature over time. The time is a cell (21x1) containing the hour at whi...

mer än ett år ago | 1 answer | 0

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Question

How to extract data from fnplt plot?
I created two plots using the fnplt function. One plot represents the chord length (c) over the radial position, the other the t...

nästan 2 år ago | 0 answers | 0

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Question

How to multiply matrix with vector?
I need to find E and K as 2 separate vectors. A, B and D are matrices of their own (3x3). N and M are vectors (2x5). Mathema...

nästan 2 år ago | 1 answer | 0

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How to implement 2 vectors in a for-loop to get a matrix?
I use a for-loop to define the profile of an airfoil. It depends on sundry factors, two of which (a and b) are variables. In o...

nästan 2 år ago | 1 answer | 0

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Question

How to extract values from plot?
I created two plots using the fnplt function. One plot represents the chord length (c) over the radial position, the other the t...

nästan 2 år ago | 0 answers | 0

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Question

How to solve quadratic equation which includes a vector?
Hi, I have the following equation: V1^2 - V1*V2 - Q*Z = 0 V1 is what I need to find V2 is a known constant Q is a known v...

ungefär 2 år ago | 1 answer | 0

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Question

What function to use to solve an equation for a variable that's on both sides of the equation?
I need to find s. Every other variable is given; they're all constants except for "e" which is a vector (of 50 given values). s...

mer än 2 år ago | 2 answers | 0

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How to solve 3 interconnected equations?
I have a vecor R with 10 values M = S * 3 and S = R+M how do I connect the vector with the 2 equations in order to receive a v...

mer än 2 år ago | 1 answer | 0

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Question

How to solve a set of equations with a vector as input
I have to create a vector P that is made of 50 values ranging from 0 to 2*10^6. Then I solve 3 equations and need to receive 3 ...

mer än 2 år ago | 1 answer | 0