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Walter Roberson


Last seen: Today
49.902 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
How to draw the contour lines in MATLAB.
data = readmatrix('Sai.xlsx'); contour(data, 0.1:0.1:1) colorbar

ongeveer 3 uur ago | 0

Answered
Supress Warning in a Loop
X=X-inv(j)*f; replace with if rank(j)<length(j) X = nan; else X = X - j\f; end

ongeveer 4 uur ago | 1

Answered
How to reorder a vector one cell at a time?
Okay, so the problem is that the rules are not exactly as you describe. The algorithm Start at the top of the column, and reme...

ongeveer 13 uur ago | 0

Answered
how to solve an equation iteratively?
syms x eqn1 =200 == x*(1-(0.4*(x-1))/sqrt(2.8*2.4*x+0.4))^(-2.8/0.4); sol = solve(eqn1, x); sol = sol(imag(sol) == 0) vpa(so...

ongeveer 16 uur ago | 0

| accepted

Answered
Inverse a cell of matrices
T1inv = cellfun(@inv, T1, 'uniform', 0); However, most of the time you should avoid using inv() . It is not common that you nee...

ongeveer 16 uur ago | 0

Answered
error: Unrecognized function or variable 'y', using ode45
function main a = 0.01725*exp(2660/300); E = 2660; T0 = 300; Cao = 2; cpa = 20; cpb = 20; nao = 2*1200; nbo = 2*1200; ...

ongeveer 17 uur ago | 2

| accepted

Answered
while loop for changing vairable
theta = [-90:5:90] M = sind(theta); N = cosd(theta); T = arrayfun(@(m,n)[m^2 n^2 0 0 0 2*m*n; n^2 m^2 0 0 0 -2*...

ongeveer 18 uur ago | 0

| accepted

Answered
How to skip vpasolve empty sym inside a loop
Store the result of vpasolve into a variable. Test to see if it is empty before storing into the matrix.

ongeveer 18 uur ago | 0

| accepted

Answered
Index exceeds array bounds... need some help please!
i= [1:100]; x(i)= 100; You initialize 100 elements for i=[1:100] Tf(i+1)=x(i+1); You try to access 100+1 elements Also...

ongeveer 19 uur ago | 0

Answered
covert data as matrix
Q =(unifrnd(0,1,5,15)) save('Q.txt', 'Q', '-ascii', '-double') !cat Q.txt

1 dag ago | 1

| accepted

Answered
Why does symbolic integration return the wrong answer for this integral?
syms x a expr = 1/(1-x)^2 F = int(expr, x, 0, a) subs(F,a,x)

1 dag ago | 2

| accepted

Answered
Plot function adding line from last point in row to origin
In order to see that plot with multiple lines, your y_nudged must be 2D. The following code takes that into account. xt = x_nud...

1 dag ago | 0

Answered
Creating grid with incremental numbers around specific coordinate
N = 5; r = 2; c = 3; temp = true(N,N); gr = bwdistgeodesic(temp, c, r) + 1

1 dag ago | 0

| accepted

Answered
Table properties giving error
You have a third-party function named split on your MATLAB path. which -all split

1 dag ago | 0

| accepted

Answered
need help with this summation
zeta = reshape(linspace(0,2), 1, [], 1); %row fo = reshape(logspace(-2,0,50), [], 1, 1); %column n = reshape(1:2:101, 1,...

1 dag ago | 0

Answered
'Matrix dimensions must agree' error in matlab app designer
function botonButtonPushed(app, event) if app.menu.Value=="engranaje" app.caja.Value=1 ...

1 dag ago | 0

| accepted

Answered
why matlab calls (pixel per inch "PPI") a (dot per inch "DPI") ?
the DPI term indicates to a something related to printing terminology which is dot ink per inch unit, Although it did certainly...

1 dag ago | 0

| accepted

Answered
How can I represent the following equation in code?
w = linspace(-5,5); hejw = abs(besselh(1, exp(1j*w))); mask = 0.7943 <= hejw & hejw <= 0.8913; plot(w, hejw, 'k-'); hold...

1 dag ago | 0

Answered
how to save the output image
infile = 'ISIC_0024336.jpg'; citra=imread(infile); figure, fig1=imshow(citra); load mri V = squeeze(citra); citra3=montag...

1 dag ago | 0

| accepted

Answered
matlab gives wrong graphical display info
https://www.mathworks.com/help/matlab/creating_guis/dpi-aware-behavior-in-matlab.html

1 dag ago | 0

| accepted

Answered
Calculation of a precise point after indefinite integral
syms Sy IXX syms d R y_a = @(d,R) R*sin(d) ; q_o_a(d, R) = -(Sy/IXX)*int(y_a(d,R)*R*t,d) ; q_1 = q_o_a(pi/2, R) ; ...

1 dag ago | 0

Answered
how to estimate/evaluate the integral of a constant value function?
syms t a b real f = piecewise(0 < t & t < 1, 5, 0) int(f, t, a, b)

1 dag ago | 0

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Answered
MATLAB no longer displaying fractions in symbolic calculation.
sympref('FloatingPointOutput', false)

1 dag ago | 1

| accepted

Answered
An efficient way to compute many sums with different number of terms
cumsum() and index it by the values

1 dag ago | 0

Answered
Determine Critical Points Numerically
EA=30000; alpha=30; beta=30; gamma=180-(alpha+beta); a=20; n=6; L_ab=a; L_bc=(a*sind(alpha))/(sind(beta)); L_ac=(a*sind(...

1 dag ago | 0

Answered
Can we plot streamilnes, isotherms and isocontour plots in MATLAB?
streamline: https://www.mathworks.com/help/matlab/ref/streamline.html Isotherms would be https://www.mathworks.com/help/matlab...

1 dag ago | 0

| accepted

Answered
Need to figure out how to find the average.
You are intended to loop over the rows for this task, not process the entire data first. Extract a row. Take nanmean of the row...

1 dag ago | 0

Answered
How do I only show 1 output instead of all the outputs as a result of the matrix
num = randi(10,3,2); [row1,col1]=size(num); foundit = false; for a=1:row1 for b=1:col1 if num(a,b) == 7 ...

1 dag ago | 1

| accepted

Answered
What is wrong with this optimization code using fmincon?
OBJFUN = @(A) 1/N *sum ( ( ( GeRT_model(A) .- GeRT_exp ) ./ GeRT_exp ).^2 ); ^^ ...

1 dag ago | 0

Answered
How do I find the average/mean of each row if the data has 150 rows and 3 columns?
A = 'measurements'; That assigns the character vector ['m' 'e' 'a' 's' 'u' etc] to A, not the content of a variable named measu...

1 dag ago | 0

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