How to Use a Function in a Loop in Mathematica?

[ggeo1]

Hello, i have this formula to iterate(attached).
It is hermite's polynomial .

I wanted to ask if in order to access A_i(x) , where A is another function ,

can i do this ?

...
suma = 0; sumb = 0;
For[i = 1, i <= n, i++,
 suma +=[B][SIZE="4"] a[x][[i]][/B]*Cos[Pi*x] ;    (a is A)
 sumb += b[x][[i]]*D[Cos[Pi*x], x];
...

 

[Bill Simpson]

If A really is a list of functions, perhaps something like this might work:

In[8]:=af1[x_]:=Cos[x];af2[x_]:=2*Sin[x];a={af1,af2};a[[1]][x]+a[[2]][x]
Out[8]=Cos[x]+2 Sin[x]

Then this might work:
In[4]:=n=2;
af1[x_]:=Cos[x];af2[x_]:=2*Sin[x];a={af1,af2};
bf1[x_]:=Tan[x];bf2[x_]:=Exp[x];b={bf1,bf2};
suma=Sum[a[][x]*Cos[Pi*x],{i,1,n}];
sumb=Sum[b[][x]*D[Cos[Pi*x],x],{i,1,n}];

 

[ggeo1]

Ok ,thanks ,i will check it.

It must be right.I didn't know how to put a function into a loop.But ,as you did,you must make a list of the function in order to do that.

Thanks again!