gamma - The gamma function.
gamma(x) evaluates the gamma function at all the elements of x. The gamma function is defined by :
/+oo
| x-1 -t
gamma(x) = | t e dt
/0
and generalizes the factorial function for real numbers (gamma(n+1) = n!).
// simple examples
gamma(0.5)
gamma(6)-prod(1:5)
// the graph of the Gamma function on [a,b]
a = -3; b = 5;
x = linspace(a,b,40000)';
y = gamma(x);
xbasc()
c=xget("color")
xset("color",2)
plot2d(x, y, style=0, axesflag=5, rect=[a, -10, b, 10])
xset("color",c)
fs=xget("font")
xset("font",4,2)
xtitle("The gamma function on ["+string(a)+","+string(b)+"]")
xset("font",fs(1),fs(2))
xselect()