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James Akula


Harvard Medical School

Last seen: 2 months ago Active since 2015

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Answered
Alphashape boundary detection not working as desired
An answer that seems to work is to convert the alphashape into a triangulation and then use "boundaryshape." load XY.mat s...

9 months ago | 0

| accepted

Question


Alphashape boundary detection not working as desired
Given a complex set of (x, y) data I would like to create a hull that is not convex but not fully conforming. I (think I) prefe...

9 months ago | 3 answers | 0

3

answers

Question


min and max Functions Breaking After Conversion From Symbolic to MATLAB Function
If I have a function whose values I want to constrain between some minimum and maximum values, I can use the min and max command...

10 months ago | 1 answer | 1

1

answer

Question


How best to change the colors of pixels in an image with known X (column) Y (row) coordinates?
The obvious way is to loop over every XY pair and change the color of the identified pixel, but this is very slow. I can do a l...

1 year ago | 1 answer | 0

1

answer

Question


matlabFunction: Why the extra ".0" and why only sometimes?
f = @(x)2.^x.*x.^2 f = sym(f) f = matlabFunction(f) While functionally irrelevant, it makes formulae difficult to read. Wh...

1 year ago | 1 answer | 0

1

answer

Answered
Comparing two curve fits (using AIC?)
I belive the following functions perform the AIC test, as shown in https://www.mathworks.com/matlabcentral/answers/1893055-compa...

1 year ago | 0

| accepted

Question


Comparing two curve fits (using AIC?)
Hello all, Let's say for a moment I have some a priori ideas about a family of functions that might best describe a particula...

1 year ago | 2 answers | 0

2

answers

Question


Can the efficienty of this code be improved, either computationally or just in terms of lines of code?
Dumb question for a smart person who has a moment to kill. Let's say I have data that will come in from n groups, and I know a ...

1 year ago | 2 answers | 0

2

answers

Submitted


Fit Circle to Weighted (x,y,w) Data
This program fits a circle to weighted set of 2D data.

2 years ago | 2 downloads |

Answered
Pairwise post-hoc testing using coefTest
I do believe I answered the question. Adding the following code to the problem seems to give me the answer I want. Uncommentin...

2 years ago | 0

| accepted

Question


Pairwise post-hoc testing using coefTest
Hello, I found this post from back in 2015 but it doesn't seem to answer the question (and if it does, I am sorry that I am mis...

2 years ago | 1 answer | 0

1

answer

Question


MATLAB function and symbolic function give different answers
% Some values for the plot A = 0.5 B = 2 % MATLAB and symbolic functions generated two ways f = @(a, b, x) (a .* (x - b).^...

2 years ago | 1 answer | 0

1

answer

Question


How to determine if points fall above an arbitrary line?
Hello all, I am trying to find a way to determine if points are above or below an arbitrary line. For example, the code numXY...

4 years ago | 1 answer | 0

1

answer

Question


Fit a conic section without mirror image hyperbola
I would like to fit conic sections to my data using something like the general form a.*x.^2+b.*x.*y+c.*y.^2+d.*x+e.*y+f. I have...

4 years ago | 2 answers | 1

2

answers

Question


Determining units for a variable
Hi all, I think I know the answer for the specific problem below, but I wonder if there is a more general process that could...

5 years ago | 1 answer | 0

1

answer

Question


Looking to duplicate SPSS MIXED in MATLAB
I have a repeated measures data-set with some missing data. Subjects from three different groups were randomly assigned to eith...

5 years ago | 0 answers | 0

0

answers

Question


Finding points of zero slope from 3D function
I will be fitting 3D differences of Gaussians to data, and from these fits I want to be able to identify troughs and peaks (poin...

6 years ago | 1 answer | 0

1

answer

Question


Solve cannot find solutions where plotting shows they exist
I am trying to find points in a function, after fitting to some data, where the slope is zero. The obvious (to me) way to do th...

7 years ago | 1 answer | 0

1

answer

Question


Converting from Zernike's Polynomials values to a Point Spread and Modulation Transfer Function
Dear all, I have a dataset obtained from a wavefront sensor that provides me with the values of the first 36 Zernike's Polyno...

8 years ago | 1 answer | 0

1

answer