10 ! ! REM ATN ! 15 ! ! KEYED IN BY TIMOTHY SHANE MCCOY ! AT CENTRAL STATE UNIVERSITY ! ON PDP 11/45 ! VERSION RSTS/E V06C ! 20 INPUT X 30 S,A = 0 40 IF ABS(X) > 1 THEN 300 50 FOR N = 1 TO 100 55 S1 = -S1 60 P = 1 70 FOR J = 1 TO 2*N-1 80 P = P * X 90 NEXT J 100 S = S + S1 * P/(2*N-1) 110 IF ABS(A-S) < 1E - 6 THEN 400 120 A = S 130 NEXT N 140 GOTO 420 300 S = 1.570796326794897 310 S1 = 1 320 FOR N = 1 TO 100 325 S1 = -S1 330 P = 1 340 FOR J = 1 TO 2*N-1 350 P = P * X 360 NEXT J 370 S = S + S1/(P*(2*N-1)) 380 IF ABS(S-A) < 1E-6 THEN 400 385 A = S 390 NEXT N 395 GOTO 420 400 PRINT "DID CONVERGE" 410 GOTO 430 420 PRINT "DID NOT CONVERGE" 430 PRINT "SUM ="S,"ATN(X) ="ATN(X) 435 PRINT N 440 GOTO 10 500 END