29.9 Mathematical functions for floating-point types [c.math]
double       laguerre(unsigned n, double x);
float        laguerref(unsigned n, float x);
long double  laguerrel(unsigned n, long double x);
Effects: 
These functions compute the Laguerre polynomials
of their respective arguments
n and x.
Returns: 
Ln(x)=exn!dndxn(xne−x),for x≥0
where
n is n and
x is x.
Remarks: 
The effect of calling each of these functions
is implementation-defined
if n >= 128.