RosettaCodeData/Task/Arithmetic-geometric-mean/ANSI-BASIC/arithmetic-geometric-mean.basic

100 PROGRAM ArithmeticGeometricMean
110 FUNCTION AGM (A, G)
120    DO
130       LET TA = (A + G) / 2
140       LET G = SQR(A * G)
150       LET Tmp = A
160       LET A = TA
170       LET TA = Tmp
180    LOOP UNTIL A = TA
190    LET AGM = A
200 END FUNCTION
210 REM ********************
220 PRINT AGM(1, 1 / SQR(2))
230 END