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David Gillcrist


Last seen: 10 dagar ago Active since 2021

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Computational Mathematics Ph.D. student

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A naive question regarding MATLABs definition of parabolic/elliptical PDEs (pdepe)
This is a shortly put question, and possibly very obvious, but MATLAB says in the documentation of pdepe (here) that is solves 1...

ungefär 2 månader ago | 1 answer | 0

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Question


What is the mathematical form called for PDEs used with the MATLAB function pdepe?
The MATLAB function pdepe (documentation here) requires that the form of the PDE being solved for is Where is the flux term,...

2 månader ago | 1 answer | 0

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answer

Question


Trying to increase the maximum width of OuterPosition (plot is cut off)
I have the following code f = figure(); f.Units = "inches"; f.OuterPosition = [0 0 7 2.5] ax1 = axes(f,'Units','inches','Pos...

3 månader ago | 0 answers | 0

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answers

Question


Apply colormap coloring to a particular contour to indicate imaginary component
I have a set of data , , , related via a function , where the data stored in are complex valued. I want to make a contour plot ...

4 månader ago | 1 answer | 0

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Question


Get quiver plot arrows to connect up contour lines
I have the following code here that plots a contour plot for a given function and also plots a color-indicated directional field...

4 månader ago | 2 answers | 0

2

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How to get the value of slopes of pchip at the enpoints?
I'm using pchip to interpolate a set of data X. After getting the interpolation, I'm trying to have functions g and f, connect t...

6 månader ago | 2 answers | 1

2

answers

Question


Can't get proper numerical convergence for complicated Advection-Diffusion-Reaction PDE
I have written an advection-diffusion-reaction PDE using a Crank-Nicolson finite difference scheme. The detail of which and the ...

7 månader ago | 0 answers | 0

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Answered
Using angdiff with pdist2 for angle data
I found a solution. I defined a new function called delta = myAngDiff(alpha,beta) which takes is expected to take a single v...

9 månader ago | 0

| accepted

Question


Using angdiff with pdist2 for angle data
I have two sets of data phi1 and phi2, and I'd like to know what the pairwise distances are for these two sets. I've tried apply...

9 månader ago | 1 answer | 0

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Question


Take the product of two probability density function histograms generated from data
I have two different sets of data $D_1$ and $D_2$ both of which have data between two values $a$ and $b$. I know I can get the h...

9 månader ago | 1 answer | 0

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Question


Best way to count outputs for a 2D polynomial function along the curve of an implicit equation
I have a 2D polynomial function given by , I also I have a contour for this function . I would like find what the distribution o...

10 månader ago | 1 answer | 0

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Question


Is there a MATLAB official way to increase/decrease line length/icon size in legends?
I'm making a a plot where the legend is quite long, here is minimal working example plot(rand(4)) lgd = legend(["Directional D...

10 månader ago | 1 answer | 0

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Question


Integrate polar histogram values about a certain value
I have a set of directional (circular) data, and I also have the mean value of this data. I need to find out how to integrate th...

10 månader ago | 1 answer | 0

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Question


Most efficient way to put vector on the off-diagonal of the blocks of a block matrix
I have two vectors each of the same length, and I want to put these vectors on the diagonal parts of each block of a matrix. Let...

ungefär ett år ago | 3 answers | 0

3

answers

Question


How can I write an array to a txt file such that it looks like MATLAB syntax
If I have an array, for example A = [1 2 3 4; -1 0 1 2; 3 9 5 7; 12 100 1000 1012]; How can I write this to a text file...

ungefär ett år ago | 1 answer | 0

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Question


How to save a function handle to a .m file
If I create a function via inline, e.g. myfunc = @(x,y,z) x.^2+y+z How can I save this as a matlab file function? I can do thi...

ungefär ett år ago | 2 answers | 0

2

answers

Question


How to sort the rows of an array by the total number of zeros in the row
I have any array where each row is a unique vector index, I want to sort the array so that column by column the numbers increase...

mer än ett år ago | 1 answer | 0

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answer

Question


How to get around sparse row deletion for least squares calculation
I have an alrogithm that repeats a reduced basis calculation for a sparse block digaonal matrix Psi. Here Psi is composed of d ...

mer än ett år ago | 2 answers | 0

2

answers

Question


Assigning values to a vector out of order in parallel (parfor)
I have a code where I'm trying to assign chunks of values to a vector out of order in a parfor loop, where the placement is dete...

mer än ett år ago | 1 answer | 0

1

answer

Answered
Assign a row vector to a row of an array using logical indexing to omit certain values
I feel embarassed to answer my own question only a short while after giving it some though, but the solution is quite simple rea...

mer än ett år ago | 0

| accepted

Question


Assign a row vector to a row of an array using logical indexing to omit certain values
I have a function, , that outputs a vector of numerical values, I also have two matrices, , the former matrix is an array of zer...

mer än ett år ago | 3 answers | 0

3

answers

Question


How to write as symbolic piecewise function with conditions on a symbolic vector
I have a symbolic vector, and I want to define a function that is an parabola if the vector is inside a hyper cube of length 2 ...

mer än ett år ago | 2 answers | 0

2

answers

Question


How to save an indefinite number of outputs to a struct
I have a function that depending on the number of inputs I give it, it will give the same number of outputs. I want a way that I...

mer än ett år ago | 2 answers | 0

2

answers

Question


Best way to speed up (parallelize) a large function that take three large 3D arrays as input
I have a function that I generated that is the doubled integral evaluated via trapezoidal rule using 1000 segments of another fu...

mer än ett år ago | 1 answer | 0

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answer

Question


The order of accuracy for my Crank-Nicolson scheme is wrong.
I've been trying to figure out what the issue is in my numerical scheme I've written to solve the particle in the box problem fo...

nästan 3 år ago | 0 answers | 0

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Question


How can I declare an implicit variable, y(t), after I have used it in a symbolically defined function?
I'm writing a scheme that solves an ODE and in doing so I declare a symbolic function: syms t y(t) f = t^(-2) * (sin(2*t) - 2*...

ungefär 3 år ago | 1 answer | 0

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