# David Wilson

### Auckland University of Technology

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**Feeds**

Runge-Kutta 4th order method

Wow, you haven't given us too much to go on, so that makes a real challenge. First up, your 2nd order ODE is needlessly comple...

3 years ago | 0

Close-loop TF Calculation

You need a few multiplies. s = tf('s') Gc= 32.8802*(s+3)/s/(s+7)/(s+8.52) Now you can perform step or bode or whatever.

3 years ago | 1

How to calculate the area between two curves

Try the following : I've used one of the many interpolation routines, but I notice that you have not sorted your (x2, y2) data, ...

3 years ago | 0

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Range-Kutta solving error.

Seems fine to me: Let's try to check the analhytical solution, and also find the derivative of F(t). That's pretty easy: clc...

3 years ago | 1

Why when I try to LLSQ fit to a quadratic the line of best fit has so many lines

A simple fix is to replace your independent variable with a variable ordered from min to max % xx = x xx = linspace(50, 230)';...

4 years ago | 2

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Filling the area between curves (loglog)

I too had some difficulty to do this elgantly. I changed the name of your data file, and commented out the material that didn't ...

4 years ago | 0

How to solve the riccati equations in matlab

Well, if Google translate is accurate, you seem to want to solve for the matrix Q. I'm assuming that everything is a matrix w...

4 years ago | 1

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How to solve the riccati equations in matlab

Do you have the control toolbox? I suspect that you could use are.m and related friends.

4 years ago | 0

How to find time constants from given 2+ order transfer function?

If you just want to display the transfer function in time-constant form, you can do the following: s = tf('s'); k = 45; % an...

4 years ago | 1

i am trying to made a code to int the numbers of time i want

Remove the z=x^2 from the loop. syms x n y z a; n= 5 z=x^2; for y=1:n z=int(z) end

4 years ago | 1

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How to obtain regression polynomial equation with more than 2 independent variables with degree 5.

OK, the fitting is easy, the plotting less so. Since you didn't give us too many hints, not did you give us any data to work wit...

4 years ago | 2

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Text keeps going behind topographic map

Your mountains are covering the text (as they should). So you need to write your text above the highest peak, so that it is seen...

4 years ago | 0

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function to produce line graph

I would strongly suggest you don't try a polynomial fit here. From the context (which you neglected to tell us), I suspect that ...

4 years ago | 0

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creating a transfer function from a determinant

How about: [num,den] = numden(G_vel) G_vel_tf = tf(sym2poly(num), sym2poly(den))

5 years ago | 0

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Problem Calculating Nonlinear Indefinite Integral

Since you neglected to tell us values for a and b, I'll just set them to a=2 and b=1. You have also two definitions for g(x), so...

5 years ago | 0

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Plot electric potential distribution

Well I kind of get what you want, but you do seem to have a singularity at the origin when r=0. p = 1; sig = 1; % constants th...

5 years ago | 1

fitting scatter data into multiple cosine functions

Yes, but it is always tricky to fit such sinusoids without good starting estimates. I'm going to use lsqcurvefit from the optimi...

5 years ago | 0

Question

Is the Moving Variance block in Simulink vectorised?

I'm using the Moving Variance block in Simulink and it seems to be giving unexplained results for vectorised (muxed) inputs. My ...

5 years ago | 1 answer | 0

### 1

answer2D Convolution - Sobel Filter. What is wrong?

Here's my (old) code for a sobel filter: img = imread('Davis_Hall.jpg'); % 'Davis_Hall.jpg':color image X =double(rgb2gray(i...

5 years ago | 1

Related to Matlab Step Comment

You are possibly confusing the closed loop response with the open loop. The closed loop gain is 1/4, so the error is 1-1/4 = 3/4...

5 years ago | 1

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how to solve matrix differential equation

Here's my attempt: M = [ 97227/21875, 0, 82269/109375, 0, 67311/43750, 0, -97227/218750, 0; ... 0, 97227/21875, 0, 822...

5 years ago | 1

From Fir2 output to transfer function

tr_fun should be a discrete transfer function, (not continuous) say tr_fun=tf(BF,1,1); % Generate a DISCRETE Transfer Function...

5 years ago | 0

How to identify corners of data plotted to estimate data between corners

How about using interp1 with the 'pchip' option? You did speculate the interpolation is overly complex, but then again it is onl...

5 years ago | 1

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How I can find co ordinates of intersection of two curves ?

Oh, looks like this is a common question: See (from 2016)https://au.mathworks.com/matlabcentral/answers/318475-how-to-find-the-i...

5 years ago | 1

Iterative Method of solving multiple variables without using the curvefit tool

Here's my attempt at fitting uusing lsqcurvefit from the optimisation toolbox. First I generate some synthetic data to subsequ...

5 years ago | 0

how can i calculate the angle of each gradient and x axis?

You could always differentiate to get the slope and then take the arc-tan. syms x real s = 1/(1 + exp(-2*(x-4))) dsdx = dif...

5 years ago | 0

Extracting the daily time series from a text file to a single column

A quick hack is: fname = 'D59.txt' Flow = []; fid=fopen(fname); Yr = 2012; R = []; while 1 tline = fgetl(fi...

5 years ago | 0

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How to Rearrange data?

Try something like the following: First read in the data file (which I've called numData.txt). I've used your test data above. ...

5 years ago | 0

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(Food for Thought) Peak Detection on ECG signal

OK, here's my (ugly) solution (withou using findpeaks). I've re-named your data set, and did some pre-processig. load ecg y =...

5 years ago | 0

| accepted