# David Gillcrist

Last seen: ungefär en månad ago Active since 2021

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Computational Mathematics Ph.D. student

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Question

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...

5 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,...

5 månader ago | 1 answer | 0

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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...

6 månader ago | 0 answers | 0

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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 ...

7 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...

7 månader ago | 2 answers | 0

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Question

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...

8 månader ago | 2 answers | 1

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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 ...

10 månader ago | 0 answers | 0

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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...

12 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...

12 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...

12 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...

ungefär ett år 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...

ungefär ett år 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...

ungefär ett år 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...

mer än ett år ago | 3 answers | 0

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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...

mer än 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...

mer än ett år ago | 2 answers | 0

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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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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

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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

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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

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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

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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...

nästan 2 år ago | 2 answers | 0

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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...

nästan 2 år ago | 1 answer | 0

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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...

ungefär 3 år ago | 0 answers | 0