# Walter Roberson

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 T0099119; if you are waiting on a reply from me for an older issue, please send me a reminder.

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C, MATLAB, Shell, Perl, Fortran

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English

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**Content Feed**

How do I fix the error of arrays having incompatible sizes?

Yes, you need to loop over KC values. Your ndt is a vector with values calculated in terms of KC. And that means that X(1:floo...

circa 18 ore fa | 0

Please help with fsolve, i keep getting this error

Your posted code has Q0 = [120;21;24;23]; which is fine. But your error message is from running some other code -- code that...

circa 18 ore fa | 0

Error while creating fitness function

It looks to me as if you ran the function by pressing the green Run button. But possibly there is a place in SparrowSearchAlgori...

circa 18 ore fa | 0

pass input arguments of built in function as cell array or structure?

feval('plot', S{:}) feval does not support passing in any kind of structured input . Most functions do not support providing s...

circa 18 ore fa | 0

| accettato

Why am I getting an error here?

function I = simpson(f,a,b) depth 1 for i = 0:n depth 2 if i==0 || i==n depth 3 elseif mod(i,2)~=0 depth 3 elseif mod(i,...

circa 19 ore fa | 0

How do I plot a prod function in MATLAB?

syms t N ht = 2 * symprod((t-5)/4, t, 1, N) T = 1:10; y = double(subs(ht, N, T)) plot(T, y)

circa 20 ore fa | 0

i don't know code

x=[10 20 30 40 50 60 70]; That is a numeric vector. f(x)=1./(cosd(x)+2*sind(x)).^2; The right-hand side calculates a vector o...

1 giorno fa | 1

Coloring string, fprintf seems limited and cprintf is even a thing?

cprintf is a File Exchange contribution. You can install it using the Add-On Explorer. The return value from fprintf() is the n...

1 giorno fa | 0

Error: Array indices must be positive integers or logical values. implementing fletcher reeves method

fletcherreeves2([5;5],@(x) x(1)^2-x(1)*x(2)+4*x(2)^2+3*x(1)+2,@(x) [2*x(1)-x(2)+3,-x(1)+8*x(2)],10^-(6)) The third parameter th...

2 giorni fa | 0

Can it be possible to use a for loop to precise the code

%%% The following lines need to be in squeezed so that it will save time (using for loop) Using a for loop is only faster th...

3 giorni fa | 0

| accettato

Can we use standard deviation of color image as a contrast value?

That particular kind of contrast is called RMS contrast; there are other contrast measures as well. https://en.wikipedia.org/wi...

3 giorni fa | 0

How can I calculate ln(x) in matlab code?

There seems to be some conception that "ln" is the "right" way to take natural logarithm, and that MATLAB is... deficient... bec...

3 giorni fa | 0

houw can I get the number of terms?

First realize that the sum of 2 cube + 4 cube + 6 cube and so on, is 2 cube times (1 cube + 2 cube + 3 cube +...) Now look u...

3 giorni fa | 0

'Unable to concatenate the table variables 'Var1' and 'Var2', because their types are cell and double.' why this error is showing?

Your file contains a mix of text and numeric. What result are you expecting when you ask to convert it to a single array?

3 giorni fa | 1

why plot line style not change?

you are plotting only one point at a time. plot() only draws lines when there are at least two adjacent finite coordinates in a ...

4 giorni fa | 1

Arrazy size problem at line 24

P= (-m)*(Acc); p=fft(P); m is a scalar and Acc has 6 elements so P has 6 elements. fft with one parameter returns someth...

4 giorni fa | 0

Summing over indices using symsum

You cannot use a symbolic variable as an index. I think it is unlikely that it will ever be supported to use symbolic variable...

4 giorni fa | 1

can we make 3D mash plot from eq y(x)

syms x theta g=9.81; v0=25; y0=1; fun = (-1)*(tand(theta)*x-(g/(2*v0^2*cosd(theta)^2)*x.^2)+y0); fsurf(fun, [0 300, 0 90]...

4 giorni fa | 0

Pre-built functions suddenly became undefined in app designer?

if timerfind() returns empty then it is [] that it returns rather than an empty array of class timer. And stop([]) does not work...

5 giorni fa | 0

make function to plot countour and 3D

f=@(X,Y) 2+X-Y+2*X.^2+2*X.*Y+Y.^2; plot3dfunc(f,-2,0,0,3) function plot3dfunc(f,Xmin,Xmax,Ymin,Ymax) x=linspace(Xmin,Xmax,5...

5 giorni fa | 0

| accettato

Add an image to subplot

axis image after you display the plot. This will set the aspect ratio to square so that the image does not get streched wide.

5 giorni fa | 1

| accettato

1*0 empty double row vector

19 < X is never true, so find() is going to return empty. What result were you hoping for in the case where the input value is ...

5 giorni fa | 0

Help in writing a a code for an array based on comdition.

See sum sign However, your description does not match your example. You say you want to replace positive numbers with 1, but yo...

5 giorni fa | 0

Slove function return empty solutions

Use dsolve for differential equations

5 giorni fa | 1

For loop variable error

m_for_k = [m1 m2]; vector. K_ex(i) = m_for_k * wn(i)^2; vector times scalar gives vector. Vector cannot be stored i...

5 giorni fa | 0

| accettato

I was plotting some data in loglog scale "Errors against step sizes" but my curve is not connected , and i can not fix it, what is the problem?

Some of your simp_err are exactly 0 but log plots cannot draw exact 0 (or negative) so the plot disconnects there. This happe...

5 giorni fa | 0

Array not compatible error

You are using diff() thinking that you are getting derivatives. However you are taking diff() of numeric matrices and diff() of ...

5 giorni fa | 0

Problems with Yticks, help?

Ticks are only drawn if they fit within the axes limits. The default axes limits are determined by rounding the range of data. Y...

5 giorni fa | 0

Error using fieldnames. Invalid argument of type 'cell'. Input must be a structure or a Java or COM object.

If you look near line 240 of https://github.com/netstim/leaddbs/blob/master/ea_normalize_ants.m you will see that the code assum...

5 giorni fa | 1

How do I create an arithmetic sequence using the counter function, but only using basic mathematics operations (in this case, addition)

i = 1; while i <= N sq(end+1) = sq(end) + d; i = i + 1; end

6 giorni fa | 0