# Matt J

Professional Interests: medical image processing, optimization algorithms

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**Content Feed**

Why is x(:) so much slower than reshape(x,N,1) with complex arrays?

I was just told by Tech Support that the issue was fixed in R2022a, but it doesn't appear that way: Nx = 256; Ny = 256; Nz = ...

23 hours ago | 0

Submitted

Absolute Orientation - Horn's method

Solves weighted absolute orientation problem using Horn's quaternion-based method.

2 days ago | 29 downloads |

How to do quadratic interpolation in two dimensions on a plane

I realize the interp2 is a linear interpolation technique No, you have several alternatives to linear interpolation with inter...

3 days ago | 0

How to loop through each row of a column, then loop through the remaining columns?

If your group1_responses is a cell or string array, there is no need to distinguish between rows and columns at all. Just do, g...

3 days ago | 1

Problem in defining the fit type function for curve fitting tool

fittype( @(nu,numGaussians,a,sigma) SCR(nu,numGaussians,a,sigma),'independent','nu')

3 days ago | 0

What is the recommended way to pass long list of parameters between main workspace and function?

In the case of your posted example, the appropriate re-implementation would be, a=1:5; result=calcvalues(a); function accum...

3 days ago | 0

Update multiple values in a struct array

You can do it in 2 lines, C=num2cell([S.value]+5); [S.value]=deal(C{:})

3 days ago | 0

Update multiple values in a struct array

No, but easy enough to make one: [s(1:2).f]=deal(1,2); s.f s=incremStruct(s,'f',5); s.f function S=incremStruct(S,field...

3 days ago | 0

how does the xcorr fun works and what is the difference between corr and xcorr?

What xcorr is computing is described here, https://www.mathworks.com/help/matlab/ref/xcorr.html#mw_ff426c84-793b-4341-86f0-077e...

3 days ago | 0

how to plot only non zero value of a slicing of a 3d matrix?

a(~a)=nan; plot(a(:,:))

3 days ago | 0

| accepted

Cosine similarity between two matrices

I tend to prefer pdist2, UV=[U(:),V(:)]; D=1-pdist2(UV,UV,'cosine')

3 days ago | 0

Constrained optimization of a vector

You have two equations so, as long as numel(a)=2 and f1 and f2 are differentiable, you can use fsolve. If numel(a)>2 then you ha...

3 days ago | 0

Fourier transform of a rectangular pulse

It's always good to decide on both your time and frequency sampling axes first, before doing any FFT processing. For a pulse wid...

4 days ago | 0

Plot plane using a line and a point?

x1=86;y1=115;z1=11420; x2=167;y2=70;z2=9240; x3=167;y3=115;z3=9240; p=null([x1,y1,z1,1; ... x2,y2,z2,1; ... ...

4 days ago | 0

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Is the 8th term maximum in the curve fitting toolbox and command line?

Perhaps just do an FFT decomposition and select the 10 strongest frequencies.

4 days ago | 0

Is the 8th term maximum in the curve fitting toolbox and command line?

You will probably have to use a custom model, or else resort to lsqcurvefit().

4 days ago | 0

How to limit variables in input function?

It does not make sense to have a tilde as an input argument in a function call. Perhaps you meant, tcfun3(1,P_min11 (j), T, 1)...

4 days ago | 0

I want to compare each element in 2 matrix same size and display a text in every case.

A=[1 2 3 4 5]; B=[2 4 9 8 2 ]; t=["no", "yes"]; t((A<B)+1)

5 days ago | 0

| accepted

Are recursively defined or nested anonymous functions dangerous?

I don't know about dangerous, but it is definitely inefficient and harder to debug. It will run much faster if you just implemen...

5 days ago | 0

| accepted

Question

Save LiveScript as an MS Word document, but keep the equations editable

When I save a Live Script as a Word .docx file the equations are all converted to images, and therefore are not editable. Is th...

5 days ago | 0 answers | 0

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answersString array to matrix

Here's an example with comma separators instead of tabs, but it would work the same way. a=["1,2";"3,4"] c=arrayfun(@(z)st...

5 days ago | 0

| accepted

Converting a system of coordinates

You need to measure the position of at least three non-colinear 3D points in both coordinate systems. Then, you can find the map...

7 days ago | 0

Extract sub array from d-dimensional array given indices for each dimension

If you have your vd_i in a cell array V={vd_1,vd_2,...,vd_d}, you can do A(V{:})

7 days ago | 0

| accepted

How to count numbers greater than a determined value

out = cumsum( histcounts(heights,0.5:0.1:100-eps(100)) ,'reverse');

7 days ago | 0

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Change initial step length in fmincon

You have some control over the step distance used for finite differencing operations (through FiniteDifferenceStepSize), and for...

7 days ago | 0

Meshgrid orthogonal to a line in 3D Space

You can also start with an unrotated grid, then rotate it: d=[1;1;1]; d=d(:).'/norm(d); [X,Y,Z]=meshgrid(-5:5); R=[d;null...

7 days ago | 0

Meshgrid orthogonal to a line in 3D Space

There are also ready-made File Exchange tools you can use, like this one d=[1;1;1]; %direction of line d=d(:)./norm(d); gtP...

7 days ago | 0

Meshgrid orthogonal to a line in 3D Space

Pick a 3D direction vector for the straight line, e.g. d=[1,1,1]; Then, d=d(:)./norm(d); B=null(d.'); %basis [x...

7 days ago | 0

how can i plot a continuous unit step function without heaviside?

Hint: t=linspace(-1,3,100); u=(t>1); plot(t,u); axis padded; xlabel t; ylabel u

7 days ago | 0

| accepted