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Walter Roberson


44,607 total contributions 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.

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Answered
Integer check with a symbolic variable
if mod(p,1) == 0

3 hours ago | 0

Answered
What is the difference between structure and table?
table has a nicer output presentation, and should be more efficient in memory. It also has some useful operations especially whe...

4 hours ago | 0

| accepted

Answered
year command does not work properly
It looks to me as if you are trying to read an excel numeric date. Excel uses Jan 1 1990 as its time base. If you have an exc...

7 hours ago | 0

Answered
Trouble with DICOM values
You should be using the dicom RescaleSlope and RescaleIntercept. Convert the data to double, multiply by the slope, add the inte...

14 hours ago | 0

Answered
Calling PSCAD to Matlab
https://hvdc.ca/pscad/automationlibrary You can have MATLAB call Python to use the pscad automation libraries This tends t...

15 hours ago | 0

Answered
how to fill color outside of a map plot in matlab like an example given below
poly2mask() and repmat() [1 1 3], and set those locations in the RGB array to the maximum for your color range (typically 255 fo...

16 hours ago | 0

Answered
Attempting to Plot Multiple Answers from a Loop
You do not define a variable V in your code, but you use it in the line xn=(V*T(i))+xn and you attempt to plot it several time...

17 hours ago | 0

Answered
How to interface pscad with matlab?
http://www.ipstconf.org/papers/Proc_IPST1997/97IPST023.pdf https://www.researchgate.net/post/How_to_make_an_interface_between_M...

17 hours ago | 0

Answered
Solving Numerical Differential Equation
Use v0 = 0; you tried to use an equation as an intial condition, but that can be done only for symbolic differential equations...

17 hours ago | 0

Answered
Inserting Output of Equations into Matrix
Since n appears to be an input, you appear to be trying to solve three simultaneous equations for the single value, theta. Becau...

23 hours ago | 0

Answered
Cost of personal license for continuing my learning after my Machine Learning Coursera class ends?
If you are a student enrolled in a degree granting instituation (does not sound as if you are though) then you would be eligible...

23 hours ago | 0

Answered
empty output when indexing excel file
When you use the raw output of xlsread(), the values for dates are not in character format: they are in Excel numeric format, wh...

23 hours ago | 0

| accepted

Answered
License renewal requiring upgrade
No and Yes. If you are renewing a support contract (Software Maintenance Service), then Mathworks historically permitted you to...

1 day ago | 0

| accepted

Answered
write a dicom image with input that is not dicom
I recommend that you find an existing dicom file that has the same properties you want, and use dicominfo() to read the meta-dat...

1 day ago | 0

Answered
Licensing error: -9,57.
See https://www.mathworks.com/matlabcentral/answers/99067-why-do-i-receive-license-manager-error-9 The license path including /...

1 day ago | 0

| accepted

Answered
Symbolic computation ERROR?
Rsymproc = feval(symengine, 'random', p-3); Rsym = @() feval(symengine, Rsymproc) + 1; Now each call to Rsym() will return one...

1 day ago | 1

| accepted

Answered
Syms in a GUI
lamb = sym('lamb') ; Your use of handles suggests that you are using guide. guide cannot manage functions that have matchin...

1 day ago | 0

| accepted

Answered
How can I load variable mat file with similar name, modify them and save them again?
filename = 'AppropriateFileNameGoesHere.mat'; ds = load(filename); for i=1:num fn = sprintf('Following_%d',i); ...

1 day ago | 0

Answered
generating binary waveform with 100Mbps?
What kind of device is being interfaced with, and with which toolbox? I would expect that the answer is "NO". 100 Mbps is into ...

1 day ago | 0

Answered
How to iterate over parfor
%% mock data input_signal = zeros(1,3000); output_raw_signal = zeros(512,640,3000); AA_filtered = []; %% no need to prealloc ...

2 days ago | 0

Answered
@FinalProject_ode must return a column vector (solved)
dydt = [dPPARuFFA dPPARuPUFA dLXRuOXYST dLXRuGLUCOSE... dTF1 dTF2 dTF3 dTF4 dPPARuLXR dLXRuPUFA]; creates a row. You n...

2 days ago | 1

Answered
fsolve with a changing variable using a for loop
syms h x U g sol = solve(-(h^2-2*h*x+x^2)*(0.04)-(1025*U^2*x)/g,x); y = subs(sol, U, u(:).'); As you are looking for negative...

2 days ago | 0

Answered
Using the Mod Function to Turn a Vector (i.e. 1:15) into [1, 2, 3, 1, 2, 3, 1, 2, 3] etc.
startVector = 1:15; vec = mod(startVector - 1, 3) + 1;

2 days ago | 0

Answered
Using loglog to plot results in a y axis that is not log scaled. But matlab seems to think it is
Your data is very nearly effectively linear in log x. sum((y-log(x)).^2) is 5.4E-7 -- a pretty low residual. You can do slightly...

2 days ago | 0

Answered
I need help using for and if for plotting a function.
e_vals = 0:0.02/1071:0.02; num_e = length(e_vals); s = zeros(1, num_e); for e_idx = 1 : num_e e = e_vals(e_idx); if...

3 days ago | 0

| accepted

Answered
formula representation with matlab.
syms rho L N_r P_b = (1/2 * (1 - sqrt(rho/(2+rho)))^(2*N_r)) * symsum( nchoosek(2*N_r - 1 + L, L) * (1/2 * (1 - sqrt(rho/(2+rho...

3 days ago | 0

Answered
Issue with atan2(.)
>> atan2(0.06) Error using atan2 Not enough input arguments. >> atan2(0,0.06) ans = 0 atan(0.06) ans = 0.05...

3 days ago | 0

| accepted

Answered
Dot indexing error for naming variable
Either variable d or e exists already and is not a structure. d.(k)= uint8(b) .* uint8(b>180); The above line is a problem: k ...

3 days ago | 0

Answered
Powermod involving REALLY large integers
Even though you have set digits large enough, s=vpa((n-1)/2^r) always produces a symbolic floating point number because that is ...

3 days ago | 0

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Answered
Which Dct Algorithm is used ?
https://www.mathworks.com/help/images/ref/dct2.html#d117e44015 describes the Discrete Cosine Transfer dct2 does dct(), transpo...

3 days ago | 0

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