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Walter Roberson


Last seen: Today Active since 2011

I do not do free private consulting. If you want to bring my attention to something, send a link to the MATLAB Answers location. I am currently caught up to T0099000; if you are waiting on a reply from me for an older issue, please send me a reminder.

Programming Languages:
C++, C, MATLAB, Shell, Perl, Fortran
Spoken Languages:
English

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Answered
Using variables from a .mat data file in a user-defined function
function [Message] = decipher(window,fs) if abs(X(abs(f-(350+50*n)) < .01)) > 0.015 How is the code to know ...

4 hours ago | 0

Answered
solving multiple equations with variable later
syms x1 x2 xL1 xL2 t x3 x4 x1 = 140 + xL1; x2 = 160 + xL2; eqn1 = x1 + x2 + x3 + x4 == 300 + xL1 + xL2 lhs(eqn1) - rhs(...

4 hours ago | 0

Answered
Inverse of a matrix
if n==n Under what circumstances could that be false? p==eye(n,n) %check if p is an identity matrix You are assuming there is...

4 hours ago | 0

Answered
How to determine the coefficient from the argmin function ?
n = 5; syms X [1 n] real syms Z [1 n] real syms a1 b1 c1 eqn1 = sum((Z + (a1*X + c1)/b1).^2) parta1 = simplify(solve(diff(e...

4 hours ago | 0

Answered
How to calculate needed sample size
Remember, Probability of an event occurring at least once in n tries is 1 minus the probability that the opposite event happens...

6 hours ago | 0

Answered
Unable to perform assignment because the left and right sides have a different number of elements.
global m d k; One of those variables is not initialized as a global variable. When you declare a variable to be global, it doe...

7 hours ago | 0

Answered
what to do when array indicies exceed for , FOR loop comparision for below , trying to plot density of atmosphere, how to do the comparison ?
h(1) = 0; That is the only place you assign to h if h(t)<[11000] but you need h to be 328084 elements by the end of the l...

12 hours ago | 0

Answered
I am unable to display my output for my graph.
Because MATLAB does not have endfor or endif commands. t = [0:0.01:20]; Vo = 90; angle = [10 25 45 65 85]; g = 9.81; yo = 0...

12 hours ago | 0

Answered
Error using symengine - Division by zero.
int(MassWing,y,0,44) That integral ends up with a division by (i-j) . When rows == cols that is a division by 0. You can get a...

13 hours ago | 1

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Answered
How to plot muitiple X-axis ?
There is https://www.mathworks.com/help/matlab/creating_plots/graph-with-multiple-x-axes-and-y-axes.html#mw_ca4bd216-f46d-49cd-9...

16 hours ago | 0

Answered
How to limit my x=[]; to a range of values between 0<=x<=1.
V=1000; Q=50; Fa0=1; k=1; E=-1; x=[]; fval=[]; syms x [1 2] real syms a positive f = [Fa0*x(1)-k*a*V*(Fa0*(1-x(1)))/(Q*(1+E*...

17 hours ago | 0

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Answered
Illegal use of reserved keyword "global".
Notice the ... on the line above. You are using a continuation marker on a previous line so the global is not the first thing in...

1 day ago | 0

Answered
How to use specific vector to define axis in imagesc?
Only the first and last XData and YData are paid attention to. That used to be documented explicitly; last time I looked the doc...

1 day ago | 0

Answered
How to get the calculation amount of deep network FLOPS? Analyze Network app does not seem to count this metric?
This is quite unlikely to happen in the near future, if ever. The translation of cuda calls into machine instructions depend...

1 day ago | 0

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Answered
Sum of series (infinity upper limit), only want odd number
syms N y h w z Pi = sym(pi); symsum(1/(2*N-1) * (1 - cosh((2*N-1)*Pi*y/h)/cosh((2*N-1)*Pi*w/(2*h))) * sin((2*N-1) * Pi * z/h),...

2 days ago | 0

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Answered
Can anyone please help me with the error in the code
clc, clear all, close all d=sin(0.05*pi*(1:200)+2*pi*rand); g=randn(1,200); v1=filter(1,[1 -0.8],g); v2=filter(1,[1 0.6],g);...

2 days ago | 1

Answered
"Unable to perform assignment because the left and right sides have a different number of elements error" using find command
reference=[1 2 3 4 5 6 8 9 10]; target=[1 2 3 4 6 7 8 9 10 3 8]; index = []; complete_reference = []; for i=1:9 thisref...

2 days ago | 1

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Answered
Showing me wrong Matrix Size.
N= cell2mat(fds.Files); The Files field of a FileDataStore is a cell array of character vectors that holds file names. When you...

2 days ago | 0

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Answered
Replace number with text
Adjust to suit A = magic(7); newA = num2cell(A); mask = mod(A,5) == 0; newA(mask) = {'NO'}; newA

2 days ago | 0

Answered
Not getting Error message
AnEmptyString = ''; str2double(AnEmptyString) When you str2double() something empty, you get NaN, not empty. You need to check...

2 days ago | 0

Answered
Have problem in solution
Erf=[0.2 0.6 0.7333]; Erf is a vector. y=(-0.3725*(Erf)^2)+(1.2144*(Erf))+(0.0006); You have Erf^2 . But in MATLAB, the ^ ope...

2 days ago | 0

Answered
How to resolve the license manager error -21
The administrator of the license server needs to update the license manager software. There is nothing you can do on your side e...

3 days ago | 0

Answered
Display variable that user requests
Perhaps just give them the Workspace Browser? https://www.mathworks.com/help/matlab/ref/workspace.html You can find the names ...

3 days ago | 0

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Answered
How to view jpeg image like can scroll
https://www.mathworks.com/help/images/add-scroll-panel-to-figure.html You can use montage() to display multiple images, or you ...

3 days ago | 0

Answered
The following error occurred converting from sym to double: Unable to convert expression into double array.
When you created NM, you created it as a numeric array. You cannot "upgrade" a numeric array to be symbolic by assigning symboli...

3 days ago | 0

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Answered
The enviinfo function was used incorrectly, I don't know what went wrong.
It appears that the data file has a header that is Exposure (Ms) . This is not a standard ENVI header, but MATLAB tries to put...

3 days ago | 0

Answered
How to put a legend in Scatter3 Plot?
scatter3(score_PCA(:,1), score_PCA(:,2), score_PCA(:,3), 15, label, 'filled') That generates one graphical object legen...

3 days ago | 0

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Answered
Placing a slider control on a surf plot?
You are using surf() and you are not passing in an axes handle to surf(). In that combination, surf() is going to use gca() to...

3 days ago | 0

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Answered
integration of erf function
syms c p d cpd u x real Pi = sym(pi); phi(cpd) = 1/sqrt(2*Pi) * int(exp(-x^2/2), x, -inf, cpd) f = int(exp(-p)*phi(c*p+d), p,...

4 days ago | 0

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Answered
read unstructured data with readtable function
The table is fixed width. Use fixed width import options; https://www.mathworks.com/help/matlab/ref/matlab.io.text.fixedwidthimp...

4 days ago | 0

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