gamma

Arguments

x

scalar, vector, matrix, or hypermatrix of real numbers.

gamma can be overloaded for complex numbers or of lists, tlists or mlists.

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(u+1) = u*gamma(u)).

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()
plot2d(x, y, style=0, axesflag=5, rect=[a, -10, b, 10])
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
• factorial — factorial function : product of the n first positive integers

History