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David Wilson


Auckland University of Technology

73 total contributions since 2011

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Answered
Runge-Kutta 4th order method
First up, you will need a much smaller step size to get an accurate solution using this explicit RK4 (with no error control). I ...

17 Tage ago | 0

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Answered
How to draw Fig. 1 from the attached pdf with this code
I didn't bother draw the other 3 lines, but you just ned to make the necessary changes to gamma for that. If you run somethi...

23 Tage ago | 0

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Answered
fsurf not drawing cant explain
Do you really need to use the symbolic toolbox? Why not just plot a numerical surface? But you are right, your numbers are widel...

24 Tage ago | 0

Answered
Fitting Monod Equation with ODE45 to data using lsqcurvefit function
Here's my solution. First set up the measured data, plot it, and look to see that it is all OK. t = [0 3 5 8 9.5 11.5 14 16 ...

etwa ein Monat ago | 0

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Answered
Solve integrals with Matlab
Do you have the symbolic toolbox? If so, start with the int command. You can do both indefinite and definite integration. sy...

etwa ein Monat ago | 1

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Answered
MATLAB Help - Rolling Dice Simulation / Central Limit Theorem
A quick hack using randi and cumsum is N = 100 x = randi(6,N,6); cs = cumsum(x')'; for i=1:6 subplot(3,2,i) histogram...

etwa ein Monat ago | 0

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Answered
How to calculate the accumulated rainfall value of 1, 2, 3, 4, 5, 6 and 7 days.
Here is my solution: I notice that you've got few NaNs for about a year and a half. Your last year is also incomplete. I is...

etwa ein Monat ago | 0

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Answered
plot x axis as persentage
Below, I've plotted an arbitrary function between arbitrary limits, -5 and +37. %% x = linspace(-5,37)'; y = erf(x/20); ...

etwa ein Monat ago | 0

Answered
inline function error help(tanh)
I can, but perhaps you should use anonymous functions. The inline approach is now discouraged. Instead of what you wrote above...

etwa ein Monat ago | 0

Answered
how to plot multiple waves on one surface
Here is a mock up solution. Code is: below. I've used part of your data, but I've made up some similar data (using a sinc fun...

etwa ein Monat ago | 0

Answered
LaTex with 2 strings separated by a num2str
Use an escape (backslash) for the % errordisplay=[' $\varepsilon_{RTP}=$ ',num2str(rtep),'\%'];

etwa ein Monat ago | 1

Answered
Solving second order implicit differential equation
Just convert the 2nd order ODE into Cauchy form. You will of course need 2 initial condtions. Define x, now you original equat...

etwa ein Monat ago | 0

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Answered
Stimulating Chemical Reaction with Differential Equation on Simulink
Homework? Anyway, to get you started, take a look at my Simulink layout: I've painted the integrators yellow, and I have expli...

etwa ein Monat ago | 0

Answered
how do i rotate an airfoil points? and plot.
Does this look better? Some (small) changes to your code. I swapped your rotation direction to better follow your example pl...

etwa ein Monat ago | 2

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Answered
plotting an exponential will a matrix over time
OK, your question is a bit vauge, and there are missing bits, i.e. the start point for y. I'm assuming you are trying to solve...

etwa ein Monat ago | 0

Answered
finding lengths of an ellipse
If you need a little more help, then it pays to plot the ellipse and look at the arc lengths. t = linspace(0,2*pi)'; x = @(t)...

etwa ein Monat ago | 0

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Answered
I want to know how i can apply k-means clustering on my scatter plotted dataset.
You probably want to use kmeans. Since you didn't give us any data to workj with, nor did you give us any idea of the number o...

etwa ein Monat ago | 1

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Answered
Fitting model to titration data
For one thing, you don't assign an answer to function sseval. That's not going to help things. Here's my solution: I've re...

etwa ein Monat ago | 1

Answered
Position of two subplots with bar charts
One option is to obtain the position of the plot with the long legend, and then re-size the other to the same width. But it's pr...

etwa ein Monat ago | 0

Answered
Histogram x axis tick labels – string
Try >> get(gca,'XTicklabel') and hack that.

etwa ein Monat ago | 1

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Answered
Histogram x axis tick labels – string
Released 2016b. What's your version? >> which xticklabels C:\Program Files\MATLAB\R2018b\toolbox\matlab\graph3d\xticklabels.m...

etwa ein Monat ago | 0

Answered
Histogram x axis tick labels – string
Hack the final xticklabel x = randn(1e5,1); x= x-min(x)+1; histogram(log(x)) xlim([0,3]) xt = xticklabels; xt{end} = 'oth...

etwa ein Monat ago | 1

Answered
solving a very complicated equation implicitly
A quick answer is you probably need to dot-divide (./) the term with the (vector) rpf. 2nd point. Because I used a root finder...

etwa ein Monat ago | 0

Answered
Y-axis labels overlaps with figure when using a reversed x-axis
Ah, missed that. Nasty bug/feature. text(10,10.5e9,'x10^9') % place manually ?

etwa ein Monat ago | 0

Answered
Y-axis labels overlaps with figure when using a reversed x-axis
Yes, it seems to only happen when there is an exponent in the y-axis. And even then the exponent must have double figures. Also ...

etwa ein Monat ago | 0

Answered
solving a very complicated equation implicitly
OK, try this: My approach was to embed an integral inside a root solver. I basically used your code and coefficients, but chan...

etwa ein Monat ago | 1

Answered
How can I find the coefficients of a second order ODE using data points?
You will also need to have collected x(t) at each sample point.

etwa ein Monat ago | 0

Answered
to find the root of quantum transcendental equation
Well you have given us quite a puzzler; little background info and no context. I'm assuming you are looking for the value Ee s...

etwa ein Monat ago | 0

Answered
How to get a kernel density plot
You also can use ksdensity from the Stats toolbox. But you have supplied us with a matrix with 25 columns! Which column were you...

etwa ein Monat ago | 0

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Answered
Coefficents not reflecting the curve obtained using fit function
I suspect that the problem is that you have normalised the data, and then forgot that when you looked at the parameter values. ...

etwa ein Monat ago | 0

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