How to plot a summation?

[Didier Lachieze]

First rule when dealing with CAS functions: avoid using upper case single letter variables such as N or X for undefined variables, use lower case variables such as n or x instead to avoid unwanted side effects. On the Prime upper-case single letter variables are predefined as reals with a default value of 0.

You don't need a program, you can do in the function app F1(X):=CAS.sum(n,n,0,X)
and you will plot steps between each integer value of X *.

If you want a nice continuous curve you can do in CAS: f:=sum(n,n,0 x)
and in the function app: F1(X)=f(X)

Do you see the difference in what you're plotting ?

*an interesting mix of lower case undefined CAS variable (n) and upper case app variable (X).