Community Profile # David Wilson

### Auckland University of Technology

Last seen: environ 2 mois ago Active since 2011

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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...

7 mois 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.

10 mois 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, ...

11 mois 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...

11 mois ago | 1

Solved

Find the standard deviation of an array

environ un an ago

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)';...

environ un an ago | 1

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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 ...

plus d'un an 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...

plus d'un an 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.

plus d'un an 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...

plus d'un an 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

plus d'un an 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...

plus d'un an 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...

plus d'un an 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 ...

plus d'un an 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))

environ 2 ans 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...

environ 2 ans 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...

environ 2 ans 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...

environ 2 ans 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 ...

environ 2 ans ago | 1 answer | 0

### 1

2D 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...

environ 2 ans 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...

plus de 2 ans 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...

plus de 2 ans 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...

plus de 2 ans 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...

plus de 2 ans 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...

plus de 2 ans 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...

plus de 2 ans 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...

plus de 2 ans 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...

plus de 2 ans 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. ...

plus de 2 ans ago | 0

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