composite function

[Volker Vogel]

Hello,

I'am trying to define composite functions,
for example this one:

      / 1 for  all x > 1
f(x) =| x*x  for all 1 >= x >= -1
      \ 1 for all x <-1

Later I want to evaluate this function with different x.
I tried to do this allready using 

symbol x("x");
string polystr="if (abs(x)>1) {1}else{x*x}";
ex poly;
poly=ex(polystr,x);
cout  << poly;

but I do not get it working. I assume that I defined
my polystr incorrect, anybody knows how to do
that ?

Grettings,

Volker Vogel





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