Gamma function: Difference between revisions

=={{header|ANSI Standard BASIC}}==

{{trans|BBC Basic}} - Lanczos method.

<syntaxhighlight lang="ansi standard basic">100 DECLARE EXTERNAL FUNCTION FNlngamma

110

120 DEF FNgamma(z) = EXP(FNlngamma(z))

130

140 FOR x = 0.1 TO 2.05 STEP 0.1

150 PRINT USING$("#.#",x), USING$("##.############", FNgamma(x))

160 NEXT x

170 END

180

190 EXTERNAL FUNCTION FNlngamma(z)

200 DIM lz(0 TO 6)

210 RESTORE

220 MAT READ lz

230 DATA 1.000000000190015, 76.18009172947146, -86.50532032941677, 24.01409824083091, -1.231739572450155, 0.0012086509738662, -0.000005395239385

240 IF z < 0.5 THEN

250 LET FNlngamma = LOG(PI / SIN(PI * z)) - FNlngamma(1.0 - z)

260 EXIT FUNCTION

270 END IF

280 LET z = z - 1.0

290 LET b = z + 5.5

300 LET a = lz(0)

310 FOR i = 1 TO 6

320 LET a = a + lz(i) / (z + i)

330 NEXT i

340 LET FNlngamma = (LOG(SQR(2*PI)) + LOG(a) - b) + LOG(b) * (z+0.5)

350 END FUNCTION</syntaxhighlight>

=={{header|BASIC256}}==

=={{header|BBC BASIC}}==