How can I graph arrays with negative exponentials? It keeps saying that there is an error but I can not figure out what is wrong

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aya risha on 9 Aug 2019

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Commented: Jon on 9 Aug 2019

Accepted Answer: Jon

%R/Dj%

x=[0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1 1.1 1.2 1.3 1.4 1.5 1.6 1.7 1.8 1.9 2];

%Dj500%

f(x)=[6.02105exp(-6,) 1.514423exp(-3), 6.64exp(-3), 1.56exp(-2), 2.79exp(-2), 4.15exp(-2), 7.50exp(-2), 1.15exp(-01), 1.42exp(-1), 1.73exp(-1), 2.12exp(-1), 2.45exp(-1), 2.55exp(-1), 2.23exp(-1), 1.56exp(-1), 7.50exp(-2), 3.10exp(-2), 1.43exp(-2), 6.88exp(-3), 4.19exp(-3), 2.81exp(-3)];

%Dj1000%

g(x)=[4.46E-06 1.35E-03 5.96E-03 1.44E-02 0.025488866 4.07E-02 7.16E-02 1.12E-01 1.40E-01 1.69E-01 2.05E-01 2.42E-01 2.44E-01 2.06E-01 1.34E-01 4.06E-02 1.79E-02 6.49E-03 2.56E-03 1.46E-03 9.67E-04];

%Dj1500%

h(x)=[2.91E-06 1.21E-03 5.33E-03 1.30E-02 2.32E-02 3.95E-02 6.56E-02 0.106300452 1.34E-01 1.62E-01 1.98E-01 2.30E-01 2.33E-01 1.80E-01 9.14E-02 2.76E-02 1.08E-02 3.21E-03 1.10E-03 5.42E-04 3.89E-04];

plot(x,f(x),g(x),h(x))

xlabel('R/DJ')

ylabel('Ma/Mr')

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Answer 1

Jon on 9 Aug 2019

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Edited: Jon on 9 Aug 2019

You need to put a multiplication operator between the constants and the exponents

f(x)=[6.02105*exp(-6,) 1.514423*exp(-3), 6.64*exp(-3), ...

also the left hand side of your statement is not valid. You should just assign the result to a variable, for example

f=[6.02105*exp(-6,) 1.514423*exp(-3), 6.64*exp(-3), ...

You also have a number of other problems,

There are some stray commas,

f(x)=[6.02105*exp(-6,)

The length of your x vector must be the same as the length of the outputs that you are plotting against it (f,g,h) in your case x has 20 elements and f,g, and h have 21.

Once you get the lengths correct

In your call to plot, you must use something like

plot(x,f,x,g,x,h)

or combine f, x,and g into a matrix and just have one x variable, e.g.

plot(x,[f;g;h])

Given the number of errors you have it seems like you are still struggling with some of the basics of using MATLAB. I would highly recommend going through the onramp training if you have not already. It should only take a couple of hours and would be well worth it if you plan on using MATLAB for your work

https://matlabacademy.mathworks.com/