Question

Calculate streamlines using ODE

Hi Matlab Gurus, I have read many posts in this forum about my problem but I'm still not capable to solve it. I'm trying with a...

meer dan een jaar ago | 1 answer | 0

Answered

i dont know why there is no anwser about this 'solve'

Your call to solve is incorrect clear all syms a b k equ2= a==20; equ3= b==20; equ1= k==sqrt((a+10)^2+b^2)-sqrt((a-10)^2+...

i dont know why there is no anwser about this 'solve'

Your call to solve is incorrect clear all syms a b k equ2= a==20; equ3= b==20; equ1= k==sqrt((a+10)^2+b^2)-sqrt((a-10)^2+...

meer dan een jaar ago | 0

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Answered

Solve system of simultaneous equations for only real numbers

I tried with a numerical solution clear all; a = [0.0094; 7.0888e-04; 0.7627; 0.1656]; c3 = 0.95; % variable mapping % ...

Solve system of simultaneous equations for only real numbers

I tried with a numerical solution clear all; a = [0.0094; 7.0888e-04; 0.7627; 0.1656]; c3 = 0.95; % variable mapping % ...

meer dan een jaar ago | 0

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Answered

select and extract only some coordinates of a 3D object

Is this what you are asking? % your code rabbit = importdata("rabbit.txt"); figure plot3(rabbit(:,1), rabbit(:,2), rabbit(:,...

select and extract only some coordinates of a 3D object

Is this what you are asking? % your code rabbit = importdata("rabbit.txt"); figure plot3(rabbit(:,1), rabbit(:,2), rabbit(:,...

meer dan een jaar ago | 0

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Answered

Convert these lines to Curves

You can interpolate your data using interp1. Warning: the interpolation may be not accurate for your trend, in this case is on...

Convert these lines to Curves

You can interpolate your data using interp1. Warning: the interpolation may be not accurate for your trend, in this case is on...

meer dan een jaar ago | 0

Answered

Numerical integration "backwards" for ODE45

you may be interested to read the comments to this post https://www.mathworks.com/matlabcentral/answers/4592-numerical-integrat...

Numerical integration "backwards" for ODE45

you may be interested to read the comments to this post https://www.mathworks.com/matlabcentral/answers/4592-numerical-integrat...

meer dan een jaar ago | 1

Answered

How to evaluate integral from 0 to inf of besselj(0,kr) * besselj(0,kR) * 1/k * (2 - e^-kz - ek(z-L)) dk

For the numerical integration, you can use integral, that also accepts Inf as integration upper bound clear variables, close al...

How to evaluate integral from 0 to inf of besselj(0,kr) * besselj(0,kR) * 1/k * (2 - e^-kz - ek(z-L)) dk

For the numerical integration, you can use integral, that also accepts Inf as integration upper bound clear variables, close al...

meer dan een jaar ago | 1

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Answered

Contourf and Surf with repeated values

Suppose you have Nx divisions along the variable of the first column and Ny divisions along the variable of the second column. Y...

Contourf and Surf with repeated values

Suppose you have Nx divisions along the variable of the first column and Ny divisions along the variable of the second column. Y...

meer dan een jaar ago | 0

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Answered

I want to write a script that reads an input text file that specifies the parameters and then uses them to solve an integral

As suggested by @Torsten your problem is a system of first order ODEs and you must use a ODE integrator. Try this clear variabl...

I want to write a script that reads an input text file that specifies the parameters and then uses them to solve an integral

As suggested by @Torsten your problem is a system of first order ODEs and you must use a ODE integrator. Try this clear variabl...

meer dan een jaar ago | 1

| accepted

Answered

Define Integral in Matlab

Suppose to have these data The simulink model is calulating you can calulate the integral in the discrete form with cumtra...

Define Integral in Matlab

Suppose to have these data The simulink model is calulating you can calulate the integral in the discrete form with cumtra...

meer dan een jaar ago | 0

Answered

How to plot faster instead of for loop?

Try using cellfun clear variables, close all load data.mat % index to [0 0; 0 0] matrices index1 = cellfun(@(x) isequal(...

How to plot faster instead of for loop?

Try using cellfun clear variables, close all load data.mat % index to [0 0; 0 0] matrices index1 = cellfun(@(x) isequal(...

meer dan een jaar ago | 0

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Answered

How to draw an Elliptical Arc by given radius (rx and ry) and start/end points ?

I am a little lazy to do the math, so I have found this reference for the two parameters a and b that describe an ellipse. http...

How to draw an Elliptical Arc by given radius (rx and ry) and start/end points ?

I am a little lazy to do the math, so I have found this reference for the two parameters a and b that describe an ellipse. http...

meer dan een jaar ago | 0

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Answered

How to plot with bar3 plot in MATLAB?

Check the code below, Hope it helps clear variables, close all B = [86, 82, 80]; B2 = [91, 88, 85]; B3 = [98, 95, 89]; ...

How to plot with bar3 plot in MATLAB?

Check the code below, Hope it helps clear variables, close all B = [86, 82, 80]; B2 = [91, 88, 85]; B3 = [98, 95, 89]; ...

bijna 2 jaar ago | 1

| accepted

Answered

How to reduce the size of legend in a fig file?

You can try playing with the 'location' optional input, for example using legend('blabla1','blabla2','Location','bestoutside') ...

How to reduce the size of legend in a fig file?

You can try playing with the 'location' optional input, for example using legend('blabla1','blabla2','Location','bestoutside') ...

bijna 2 jaar ago | 0

Answered

Convert german numbers from excel to matlab (change comma versus point)

You may try to use readtable to import your data. It reads excel files and has the option 'DecimalSeparator' that can be set to ...

Convert german numbers from excel to matlab (change comma versus point)

You may try to use readtable to import your data. It reads excel files and has the option 'DecimalSeparator' that can be set to ...

bijna 2 jaar ago | 1

| accepted

Answered

Create multiple copies of one file in multiple directories with different names

Try this. Note: the file A.txt must be in the current folder % data N = 10; dirName = 'Folder'; fileName = 'A'; % loop ...

Create multiple copies of one file in multiple directories with different names

Try this. Note: the file A.txt must be in the current folder % data N = 10; dirName = 'Folder'; fileName = 'A'; % loop ...

bijna 2 jaar ago | 0

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Answered

How to rotating a stl object

You shoud translate the points p before the rotation and then move them back If R is your rotation matrix and the center of rot...

How to rotating a stl object

You shoud translate the points p before the rotation and then move them back If R is your rotation matrix and the center of rot...

bijna 2 jaar ago | 0

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Answered

Very tricky:Manipulation with complex array

Following @Paul suggestion % original vector X = [4, 1, 1, 3, 8, 12]; % reshape to have 2xN vector W = reshape(X,2,[]); ...

Very tricky:Manipulation with complex array

Following @Paul suggestion % original vector X = [4, 1, 1, 3, 8, 12]; % reshape to have 2xN vector W = reshape(X,2,[]); ...

bijna 2 jaar ago | 0

| accepted

Answered

Minimal-code to get axes limits of log-log plots, but using gscatter

You can remove the negative part of the axis before setting the log scale set(gca,'XLim',[0 max(xlim)],'YLim',[0 max(ylim)]); ...

Minimal-code to get axes limits of log-log plots, but using gscatter

You can remove the negative part of the axis before setting the log scale set(gca,'XLim',[0 max(xlim)],'YLim',[0 max(ylim)]); ...

ongeveer 2 jaar ago | 0

Answered

How to plot Temperature vs Efficiency curve using For loop and Linspace?

I have commented your plots to avoid moltiple figures % numebr of temperatures nT = 100; % temperature vector T = linspace(2...

How to plot Temperature vs Efficiency curve using For loop and Linspace?

I have commented your plots to avoid moltiple figures % numebr of temperatures nT = 100; % temperature vector T = linspace(2...

ongeveer 2 jaar ago | 1

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Question

Calculation of consistent initial conditions for ODE

(minor edit) Hi everyone, I have written wrapper functions calling MATLAB's ODE solvers. Specifically, my problems are DAEs wi...

ongeveer 2 jaar ago | 1 answer | 0

Answered

How to find same unique in two different size arrays?

Use ismember % data x=[1 22 22 3 8 19]; y=[22 10 19 35]; % engine [iii,jjj] = ismember(y(:),x(:)); countCommon = su...

How to find same unique in two different size arrays?

Use ismember % data x=[1 22 22 3 8 19]; y=[22 10 19 35]; % engine [iii,jjj] = ismember(y(:),x(:)); countCommon = su...

ongeveer 2 jaar ago | 0

| accepted

Answered

Having trouble using for loops to create a matrix

I reproduce the result of the picture, because the question is not clear. a = 25 ; b = 5 ; c = (2*a)/b - 1 ; % do not use mi...

Having trouble using for loops to create a matrix

I reproduce the result of the picture, because the question is not clear. a = 25 ; b = 5 ; c = (2*a)/b - 1 ; % do not use mi...

ongeveer 2 jaar ago | 0

| accepted

Answered

How to plot a function

You may use fplot figure, hold on fplot(@(x)x.^-3,[1 1e5]) fplot(@(x)x.^-2.8,[1 1e5]) % use bi-logaritmic scale set(gca,'...

How to plot a function

You may use fplot figure, hold on fplot(@(x)x.^-3,[1 1e5]) fplot(@(x)x.^-2.8,[1 1e5]) % use bi-logaritmic scale set(gca,'...

ongeveer 2 jaar ago | 1

Answered

Ax = 0 with 2 values of x known

The post is old but the question arises many times, so I post here my solution. It is a generalization of @Matt J solution. Sup...

Ax = 0 with 2 values of x known

The post is old but the question arises many times, so I post here my solution. It is a generalization of @Matt J solution. Sup...

ongeveer 2 jaar ago | 0

Answered

Looking for visualization method to present finite difference numerical solution in 2D

You may use the low-level patch function. Since I don't have your data, please find below a self-consistent example showing the ...

Looking for visualization method to present finite difference numerical solution in 2D

You may use the low-level patch function. Since I don't have your data, please find below a self-consistent example showing the ...

meer dan 2 jaar ago | 0

Answered

smooth step function with rise time

My colleague Sofia have found a paper [1] where authors report the analytic approximation of the piece-wise linear step function...

smooth step function with rise time

My colleague Sofia have found a paper [1] where authors report the analytic approximation of the piece-wise linear step function...

bijna 3 jaar ago | 1

| accepted

Question

smooth step function with rise time

Hi everyone, I know this question is more related to math than Matlab, but I know there are many gurus out there who can easily...

bijna 3 jaar ago | 2 answers | 1

Answered

How can I calculate the sum of the absolute error?

Please check the code below. clear all, close all % model F = @(c,x)c(1)+c(2)*x+c(3)*(x.^2-1); % data xk = [-2 -1 0 1 ...

How can I calculate the sum of the absolute error?

Please check the code below. clear all, close all % model F = @(c,x)c(1)+c(2)*x+c(3)*(x.^2-1); % data xk = [-2 -1 0 1 ...

bijna 3 jaar ago | 1

| accepted