Plotting a function over an interval

I am trying to plot a function in which one term is (2^(-1/a))*(1+x)^(1+1/a). When a is very small, for example a=10^-4 or even smaller, this term turns to NaN. How can I plot this function?

[Torsten]

The best you can do is write your function as

(1+x).*((1+x)/2).^(1/a)

If the problem remains, (1+x)/2 is simply too large (or "a" is too small).

Best wishes

Torsten.

[Ali Baig]

Thank you. It works up to a=10^-6.

[Pieter Hamming]

Can you give a little more information about the goal of the plot? This sounds like an occasion where a (semi-)log plot would be suitable. This in turn could help in rewriting the equation

[Ali Baig]

@Pieter hamming, this is exact solution of a convection-diffusion equation. I calculated the numerical solution using Finite Element Method and the goal of the plot was to compare the two solutions.

[Pieter Hamming]

I was a bit unclear in my question, sorry. What I meant is more info about the variables involved: size, scale and such.

Is a a single value of 10^-6? Is it a set of points on an interval? If so, how many points and on what interval?

Assuming you want to plot (2^(-1/a))*(1+x)^(1+1/a) for one value of a and a range of x, what range of x do you need?

What do you want with the plot? Visually compare to a previous plot? In that case a log plot should suffice.

These kind of details help a lot in determining how we can help you best. In the future, consider adding them immediately to the question :)

[Ali Baig]

I plotted 6 different graphs. For each graph, ''a'' is constant, and its values are 10^-1, 10^-2,.., 10^-6. Variable ''x'' vary from 0 to 1, and 40 uniformly-spaced x values are used. And the purpose of the graphs is to visually compare the exact solution and the finite element solution.

Thank you for your suggestions.

[Torsten]

If x only varies from 0 to 1, you should be able to plot your graphs for whatever "a" you want with my suggestion.

[Ali Baig]

I am trying to plot for ''a'' up to 10^-6 and the simplification propsed by Hamming works up to this value.

[Torsten]

x=linspace(0,1,40);
a=1e-12;
y=(1+x).*((1+x)/2).^(1/a);
plot(x,y)

works for me.