RosettaCodeData/Task/Gamma-function/Stata/gamma-function-1.stata

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mata
_gamma_coef = 1.0,
5.772156649015328606065121e-1,
-6.558780715202538810770195e-1,
-4.200263503409523552900393e-2,
1.665386113822914895017008e-1,
-4.219773455554433674820830e-2,
-9.621971527876973562114922e-3,
7.218943246663099542395010e-3,
-1.165167591859065112113971e-3,
-2.152416741149509728157300e-4,
1.280502823881161861531986e-4,
-2.013485478078823865568939e-5,
-1.250493482142670657345359e-6,
1.133027231981695882374130e-6,
-2.056338416977607103450154e-7,
6.116095104481415817862499e-9,
5.002007644469222930055665e-9,
-1.181274570487020144588127e-9,
1.04342671169110051049154e-10,
7.782263439905071254049937e-12,
-3.696805618642205708187816e-12,
5.100370287454475979015481e-13,
-2.05832605356650678322243e-14,
-5.348122539423017982370017e-15,
1.226778628238260790158894e-15,
-1.181259301697458769513765e-16,
1.186692254751600332579777e-18,
1.412380655318031781555804e-18,
-2.298745684435370206592479e-19,
1.714406321927337433383963e-20
function gamma_(x_) {
external _gamma_coef
x = x_
y = 1
while (x<0.5) y = y/x++
while (x>1.5) y = --x*y
z = _gamma_coef[30]
x--
for (i=29; i>=1; i--) z = z*x+_gamma_coef[i]
return(y/z)
}
function map(f,a) {
n = rows(a)
p = cols(a)
b = J(n,p,.)
for (i=1; i<=n; i++) {
for (j=1; j<=p; j++) {
b[i,j] = (*f)(a[i,j])
}
}
return(b)
}
x=(1::1000)/100
u=map(&gamma(),x)
v=map(&gamma_(),x)
max(abs((v-u):/u))
end