John D'Errico
Retired
Statistics
All
MATLAB Answers
File Exchange
62 Files
Cody HighlightsRANK
9
of 299.177
REPUTATION
22.079
CONTRIBUTIONS
15 Questions
7.850 Answers
ANSWER ACCEPTANCE
46.67%
VOTES RECEIVED
4.816
RANK
4 of 20.647
REPUTATION
66.274
AVERAGE RATING
4.80
CONTRIBUTIONS
62 Files
DOWNLOADS
858
ALL TIME DOWNLOADS
598247
CONTRIBUTIONS
0 Posts
CONTRIBUTIONS
0 Public Channels
AVERAGE RATING
CONTRIBUTIONS
1 Highlight
AVERAGE NO. OF LIKES
8
Feeds
Answered
The below code takes much time to just compute till N=5. But I wanna know how to do it for N=100 or more a bit faster.
I want a bright red new Ferrari in my driveway for Christmas. Its not gonna be there of course. But we all want things we can't ...
The below code takes much time to just compute till N=5. But I wanna know how to do it for N=100 or more a bit faster.
I want a bright red new Ferrari in my driveway for Christmas. Its not gonna be there of course. But we all want things we can't ...
4 dagen ago | 0
Answered
How to merge red and blue images on white background with transparency
Easy enough, in a very lazy way too. If you kow how to do what you want with a black background, then make it so. And then back....
How to merge red and blue images on white background with transparency
Easy enough, in a very lazy way too. If you kow how to do what you want with a black background, then make it so. And then back....
5 dagen ago | 0
Answered
How to use arrayfun with built-in Matlab functions where the variable parameter is passed with 'Name', 'Value'?
I see this soooo often, people thinking arrayfun is a good way to speed up code. But, is it, really? Arrayfun is a nice tool to ...
How to use arrayfun with built-in Matlab functions where the variable parameter is passed with 'Name', 'Value'?
I see this soooo often, people thinking arrayfun is a good way to speed up code. But, is it, really? Arrayfun is a nice tool to ...
9 dagen ago | 1
Answered
solving system of equations
There is absolutely no need to use an iterative solver!!!!!!!! The idea is to remove the absolute value from your problem, and ...
solving system of equations
There is absolutely no need to use an iterative solver!!!!!!!! The idea is to remove the absolute value from your problem, and ...
14 dagen ago | 0
Answered
Can not read MAT file in another language
My guess is Julia can read a .mat file created for an earlier release of MATLAB. Looking at the help for save, you can specify a...
Can not read MAT file in another language
My guess is Julia can read a .mat file created for an earlier release of MATLAB. Looking at the help for save, you can specify a...
14 dagen ago | 0
| accepted
Answered
Trying to do an fsolve via an anonymous function
You say you want to use fzero. But you need to understand that fzero is a ONE variable solver. It CANNOT solve a multi-variable ...
Trying to do an fsolve via an anonymous function
You say you want to use fzero. But you need to understand that fzero is a ONE variable solver. It CANNOT solve a multi-variable ...
16 dagen ago | 0
Answered
Precision lost when combining Int32 integers with single precision numerical numbers
Why is MATLAB set up this way? Because you can't please all of the people, all of the time. Suppose a numeric vector could have ...
Precision lost when combining Int32 integers with single precision numerical numbers
Why is MATLAB set up this way? Because you can't please all of the people, all of the time. Suppose a numeric vector could have ...
19 dagen ago | 3
| accepted
Answered
What is the difference between A={1 2} and A = { '1','2'} and how to convert one from other ?
Think of it like this: 1 is a "number" as stored in MATLAB, as is 2. X = [1 2] whos X X is stored in double precision. We ca...
What is the difference between A={1 2} and A = { '1','2'} and how to convert one from other ?
Think of it like this: 1 is a "number" as stored in MATLAB, as is 2. X = [1 2] whos X X is stored in double precision. We ca...
23 dagen ago | 0
Answered
comparison between two optimisation algorithms
There are very, very many ways to solve a computing problem. You have chosen one of them, and it worked for you. Is the choice...
comparison between two optimisation algorithms
There are very, very many ways to solve a computing problem. You have chosen one of them, and it worked for you. Is the choice...
28 dagen ago | 0
Answered
Strange behaviour of plot
Cute. If you try this in R2025a: small = 1e-7;plot([0,small,1],[0,small,1]) small = 1e-8;plot([0,small,1],[0,small,1]) (Sorry...
Strange behaviour of plot
Cute. If you try this in R2025a: small = 1e-7;plot([0,small,1],[0,small,1]) small = 1e-8;plot([0,small,1],[0,small,1]) (Sorry...
29 dagen ago | 0
Answered
How does Matlabs svd() function calculate the value of V?
UM, You seriously do not want to use X'*X to compute anything about the SVD. Yes, mathematically, it is the same. But this is no...
How does Matlabs svd() function calculate the value of V?
UM, You seriously do not want to use X'*X to compute anything about the SVD. Yes, mathematically, it is the same. But this is no...
30 dagen ago | 1
Answered
icc rgb profile editing
You can use iccread and iccwrite. help iccread help iccwrite Having used iccread, you can modify whatever you wish, then writ...
icc rgb profile editing
You can use iccread and iccwrite. help iccread help iccwrite Having used iccread, you can modify whatever you wish, then writ...
30 dagen ago | 0
Answered
How to reduce the file size of MAT files?
NO. Rounding numbers will change nothing. MATLAB does not store double precision numbers in decimal form. So even though you thi...
How to reduce the file size of MAT files?
NO. Rounding numbers will change nothing. MATLAB does not store double precision numbers in decimal form. So even though you thi...
ongeveer een maand ago | 0
| accepted
Answered
select line by touching with mouse
"select curve?" Well, yes, in a sense. When you plot the curve, you can supply a ButtonDownFcn, so that when you click on the c...
select line by touching with mouse
"select curve?" Well, yes, in a sense. When you plot the curve, you can supply a ButtonDownFcn, so that when you click on the c...
ongeveer een maand ago | 0
Answered
Fitting a blackbody curve with two variables - having issues with lsqcurvefit stopping and unsure how to use options effectively
Your data does not seem to fit terribly well to the model you propose. c=2.998e8; h=6.6261e-34; kb=1.38e-23; %wavelgnth (x...
Fitting a blackbody curve with two variables - having issues with lsqcurvefit stopping and unsure how to use options effectively
Your data does not seem to fit terribly well to the model you propose. c=2.998e8; h=6.6261e-34; kb=1.38e-23; %wavelgnth (x...
ongeveer een maand ago | 1
| accepted
Answered
How to generate all 2^n combinations of n choices from a 2-vector?
Simple enough. Don't use combinations. n = 3; t = dec2bin(0:2^n - 1) - '0' Easy enough to make that into a table if you so de...
How to generate all 2^n combinations of n choices from a 2-vector?
Simple enough. Don't use combinations. n = 3; t = dec2bin(0:2^n - 1) - '0' Easy enough to make that into a table if you so de...
ongeveer een maand ago | 1
| accepted
Answered
Matlab 'try now' and contact customer service doesn't work
Answers is not customer support. In fact, we are generally not even employed at The MathWorks, though some TMW staff do visit th...
Matlab 'try now' and contact customer service doesn't work
Answers is not customer support. In fact, we are generally not even employed at The MathWorks, though some TMW staff do visit th...
ongeveer een maand ago | 0
| accepted
Answered
is readmatrix a built-in Matlab function part over every install after 2019a?
NO. Not for ANY release number. Some of those functions may have been introduced in different years, different releases. And if ...
is readmatrix a built-in Matlab function part over every install after 2019a?
NO. Not for ANY release number. Some of those functions may have been introduced in different years, different releases. And if ...
ongeveer een maand ago | 0
Answered
Constraints to a Second Order Curve Fit
You want to constrain the quadratic coefficient to be positive. But your data wants it to be a little bit negative. Effectively,...
Constraints to a Second Order Curve Fit
You want to constrain the quadratic coefficient to be positive. But your data wants it to be a little bit negative. Effectively,...
ongeveer 2 maanden ago | 1
Answered
Is vectorization worth the trouble with recent MATLAB?
Is vectorization worth it? Let me see. For example: Add 1 to every element of a vector. V = rand(1,1e6); % Which is itself high...
Is vectorization worth the trouble with recent MATLAB?
Is vectorization worth it? Let me see. For example: Add 1 to every element of a vector. V = rand(1,1e6); % Which is itself high...
ongeveer 2 maanden ago | 0
Answered
How to specify intervals of increasing, decreasing of a function in MATLAB
This can get fairly messy, if your function is carefully designed to cause you problems. For example, you may need to find a sin...
How to specify intervals of increasing, decreasing of a function in MATLAB
This can get fairly messy, if your function is carefully designed to cause you problems. For example, you may need to find a sin...
2 maanden ago | 1
Answered
Not exactly the exact answer using Symbolic Math Toolbox
Your problem stems from a common mistake. Whaen you write this: syms t f = sin(t); frms = sqrt(1/(2*pi)*int(f^2,t,[0 2*pi]))...
Not exactly the exact answer using Symbolic Math Toolbox
Your problem stems from a common mistake. Whaen you write this: syms t f = sin(t); frms = sqrt(1/(2*pi)*int(f^2,t,[0 2*pi]))...
2 maanden ago | 1
Answered
How does the expfit function... functions
You may be confused. Well, let me say, almost certainly, you are confused. ;-) There is a difference between curve fitting, in ...
How does the expfit function... functions
You may be confused. Well, let me say, almost certainly, you are confused. ;-) There is a difference between curve fitting, in ...
2 maanden ago | 0
Answered
No results are showing in the symbolic math computation
First, you need to recognize MATLAB is case sensitive. Your code does not run, instead, it fails in several places. I fixed it, ...
No results are showing in the symbolic math computation
First, you need to recognize MATLAB is case sensitive. Your code does not run, instead, it fails in several places. I fixed it, ...
2 maanden ago | 0
| accepted
Answered
Solving ODE just for one time step
Then I fail to see the problem. You want only the solution at the end point. % A simple ODE. with y(0) == 1, the analytical s...
Solving ODE just for one time step
Then I fail to see the problem. You want only the solution at the end point. % A simple ODE. with y(0) == 1, the analytical s...
2 maanden ago | 0
Answered
Analyzing errors of a numerical Jacobian matrix of partial derivatives, as the finite-differencing step-size gets successively smaller,
I explained EXACTLY this in my last answer to your last question. Please read what I write and think about it. If you don't then...
Analyzing errors of a numerical Jacobian matrix of partial derivatives, as the finite-differencing step-size gets successively smaller,
I explained EXACTLY this in my last answer to your last question. Please read what I write and think about it. If you don't then...
2 maanden ago | 0
| accepted
Answered
How can I reduce the "method error" with my central-difference method, when estimating a Jacobian matrix of partial derivatives?
This is a complex question, with possibly no perfect answer. For example, suppose you have a Newton method, that employs a fini...
How can I reduce the "method error" with my central-difference method, when estimating a Jacobian matrix of partial derivatives?
This is a complex question, with possibly no perfect answer. For example, suppose you have a Newton method, that employs a fini...
2 maanden ago | 3
Answered
Better package manager abstracted away from matlab versions
Why don't they have the perfect set of tools, exactly as you want them to have been written? Because MATLAB was designed to make...
Better package manager abstracted away from matlab versions
Why don't they have the perfect set of tools, exactly as you want them to have been written? Because MATLAB was designed to make...
2 maanden ago | 0
Answered
Generate n random numbers between 0.1 and 0.9 without repetition
There are always many ways to solve a problem. Here is mine: % generate the set of ALL possible combinations. There are not man...
Generate n random numbers between 0.1 and 0.9 without repetition
There are always many ways to solve a problem. Here is mine: % generate the set of ALL possible combinations. There are not man...
2 maanden ago | 0
Answered
How to get real root of a function using fminbnd?
It sounds like you want to see the result: (-1)^(4/3) == 1 To do that, you want to use nthroot, by splitting the fraction...
How to get real root of a function using fminbnd?
It sounds like you want to see the result: (-1)^(4/3) == 1 To do that, you want to use nthroot, by splitting the fraction...
2 maanden ago | 0
| accepted
