# Daniel Pollard

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**Content Feed**

why do I receive "Index in position 1 is invalid. Array indices must be positive integers or logical values"

i and j in MATLAB both have the default value of the complex unit. When you say for i = 1:26 you override this, so now i take...

9 months ago | 0

| accepted

Why vector created by colon have improper values

I'm struggling a bit to understand exactly what your question is but I think what you're asking is why the value 0.8 is not in y...

1 year ago | 1

why when i use find command to find the index i face problem

I had a play with my version of Matlab and found the same result. I think what you've stumbled on is a floating point error. The...

1 year ago | 0

All possible combination based on 2^n but with 1 and -1

You could take the answer from your previous question, subtract 0.5 and multiply by 2. Your accepted answer was n = 3; m = dec...

1 year ago | 0

How do I delete the last dimension of a 256*256*3 matrix?

Is Ii your 256x256x3 array? An image of 256x256 pixels will have 256x256x3 elements because of the red, green and blue elements....

1 year ago | 0

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Question

Is there a way to vectorise this vector/matrix product?

I have a piece of code inside a for loop, which looks like for k = 1:size(G, 1) G(k) = real(W(:,k)' * R * W(:,k)) end G ...

1 year ago | 2 answers | 0

### 2

answersCalculate power of exponential

Deleted my previous answer as I hadn't seen your edit so gave a wrong answer. You need a . before the multiplication symbol. Tr...

1 year ago | 1

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I want my solution as a Vector

Does this work? X(z) = R/N; instead of X = R/N

1 year ago | 0

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Unable to perform assignment because the size of the left side is 1-by-1 and the size of the right side is 1-by-1-by-2.

I haven't run it, but I think your code will error on the line deltaxj(i,ii,iii)=sum1+(x1-x1New)*(k.*(Rn+Rp)-dn)./dn; because...

1 year ago | 0

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How to error check a number for strings and blank inputs?

Are you looking for validateattributes or assert? For example, assert(menu == 1 || menu == 2) will throw an error if menu is n...

1 year ago | 0

FOR LOOP , beginner question.

Your code is d = []; for x=[0.1000,0.1500,0.2000] d=[d ((34.63/x)-5.126)/2.54]; disp ("ANSWER"); end x=[0.1000 0.1...

1 year ago | 0

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Can't calculate angle a, when 𝑠𝑖𝑛(𝑎)=2.

If a is a real number, then sin(a) must be between -1 and 1. Calling asin(2) returns 1.5708 - 1.3170i which is a complex num...

1 year ago | 2

| accepted

Array indices must be positive integers or logical values

You wrote psi(i,j) = ((U0*V0)./W)*cos(W(t-YY(i,j)./V0))-V0*XX(i,j); Try psi(i,j) = ((U0*V0)./W)*cos(W*(t-YY(i,j)./V0))-V0*XX(...

1 year ago | 0

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Solved

Find the largest number

Find the largest number |x| among 4 numbers given as variables |a|, |b|, |c|, and |d|. Example: Input: a = 4; b = 7; c ...

1 year ago

How to combine multiple curve fits in one plot?

https://www.mathworks.com/help/matlab/creating_plots/combine-multiple-plots.html This was literally the top result when I googl...

1 year ago | 0

Why is validateattributes returning me a Not enough inputs error only in this context?

I was assigning the class to a vector in reverse order, using a loop like for k = 16:-1:1 lsqsin(k) = LsqSinusoid(N_sample...

1 year ago | 0

| accepted

Question

Why is validateattributes returning me a Not enough inputs error only in this context?

I have a class definition called LsqSinusoid(n_samples, f, Fs). The constructor for that class takes three inputs - n_samples, t...

1 year ago | 1 answer | 0

### 1

answerWhile loop for testing the end of vector (Matlab)

If you know that it's 1-dimensional, you can use numel(vector) which returns the length of your vector. Also useful to know i...

1 year ago | 1

Finding numChanges in array

Replace for i=1;length(V) with for ii = 1:length(V) The semicolon -> colon is a typo I suspect, and i has a built in value s...

1 year ago | 1

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How to plot a graph in nm

Your method works perfectly well. An alternative option would be theta = 10 wavelength = [500:10:700] m = 1 d = (m.*waveleng...

1 year ago | 1

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Unable to perform assignment because the size of the left side is 1-by-1 and the size of the right side is 10-by-10. not sure why i am getting this error

Biot_top is size 10x10. dtMat(1,j) is size 1x1. This means the LHS of your line is 1x1, and the RHS is 10x10, so you can't make ...

1 year ago | 0

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How to create one errorbar for multiple data points?

If I understand you right, could you do something like figure; hold on plot(x, y, 'bx') errorbar(mean(x), mean(y), std(y), 'k...

1 year ago | 1

| accepted

Graph with similar axis value with the value given

You want xticks and yticks. As a note: you need the vectors to be in ascending order, and your second tickmark vector isn't. so...

1 year ago | 0

Does MathWorks have software for rocket trajectory modeling at supersonic speed?

The Aerospace toolbox is likely to be the closest to what you want. I don't use it so don't know much about it, but it seems to ...

1 year ago | 0

converting degrees and radian

Something like option = input("Type A for degree to radians, and B for radians to degrees: ", 's') if option == "A" degs ...

1 year ago | 0

How can I plot histogram?

Simply googling "matlab histogram" would have answered your question. That link is for the documentation for histogram. histog...

1 year ago | 0

Double for loop is not working properly

k will take the values [1 2]. For the first iteration of k, it stores data{1,1}(:,14) in ch{1,n}. The second time around, it wil...

1 year ago | 0

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Uneven linspacing of an array

If I understand right, you have a vector len, and you want to have a vector x such that diff(x)=len. In that case, you can use t...

1 year ago | 0

Problem with running a Matlab code.

Clear your variables by putting the command clear at the start of your programme. It's almost certainly holding onto variable...

1 year ago | 0

| accepted