gamma

Arguments

x

real vector or matrix

y

real vector or matrix with same size than x.

Description

gamma(x) evaluates the gamma function at all the elements of x. The gamma function is defined by :

and generalizes the factorial function for real numbers (gamma(n+1) = n!).

Examples

// 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);
clf()
c=xget("color")
xset("color",2)
plot2d(x, y, style=0, axesflag=5, rect=[a, -10, b, 10])
xset("color",c)
xtitle("The gamma function on ["+string(a)+","+string(b)+"]")
show_window()

See Also

• gammaln — The logarithm of gamma function.
• dlgamma — derivative of gammaln function, psi function

Authors

W. J. Cody and L. Stoltz (code from Netlib (specfun))