ON ERROR GOTO 10
DIM f AS DOUBLE, y AS DOUBLE, x AS DOUBLE, paso AS DOUBLE, j AS DOUBLE, yaux AS DOUBLE, yaux2 AS DOUBLE, yaux3 AS DOUBLE
CLS
SCREEN 12
f = 1
l = 1
yy = 1: y = 2
REM ***************** colores *******************
c1 = 8: c2 = 3: c3 = 12: c4 = 15

REM *********************** coef sirve para ampliar la imagen **************
coef = 20

REM *** paso sirve para la precison/velocidad *****************************
REM *********** ejemplo:    paso=1 ->rapido;       paso=0.05->preciso  ****
paso = .2

FOR n = 0 TO 320 / coef: LINE (n * coef + 320, 0)-(n * coef + 320, 479), c1: LINE (-n * coef + 320, 0)-(-n * coef + 320, 479), c1: NEXT
FOR n = 0 TO 240 / coef: LINE (0, n * coef + 240)-(639, n * coef + 240), c1: LINE (0, -n * coef + 240)-(639, -n * coef + 240), c1: NEXT
LINE (0, 240)-(639, 240), c2
LINE (320, 0)-(320, 479), c2

pi = 3.14159265#
coeficiente = (8 - 4 * pi) / (pi * pi * pi)

5 f = f + paso: IF ABS(f - INT(f)) < .02 THEN f = INT(f)
 IF f >= 640 THEN a$ = INPUT$(1): END
 x = (f - 320) / coef


 dy = (y - yy) / (paso / coef)
 yy = y
REM ************************* aqui va la funcion y=x... ********************
'y = 1 / (x - 1)
'y = (TAN(x)) ^ SIN(x)
'y = LOG(x - 1)
'y = INT((x / ABS(x)) + .5) * 2 / ((1 - ABS(x)) ^ 3)
'r0 = 10
'r1 = 20
' y = 10 / (1 + r0 * ((r1 + x) / (r1 * x)))
'y = x
'y = x * x
'y = 4 / 3.14159265# / 3.14159265# * x * (3.14159265# - x)
'y = x * (coeficiente * x * x + 1)
'y = x + (4 - 2 * pi) / pi / pi * x * x - 2 / pi / pi * x * x * (x - pi / 2) - 4 / pi / pi / pi * x * x * (x - pi / 2) * (x - pi)
'y = x + (4 / pi / pi - 2 / pi) * x * x - 2 * (8 - 2 * pi) / pi / pi / pi * x * x * (x - pi / 2)

j = x' + 3.14159265358979#
'Aqui va el desarrollo hasta n=31, hay 15 terminos de la serie!
yaux3 = (1 + j * j / 506 * (-1 + j * j / 600 * (1 + j * j / 702 * (-1 + j * j / 812 * (1 + j * j / 930)))))
yaux2 = (-1 + j * j / 272 * (1 + j * j / 342 * (-1 + j * j / 420 * yaux3)))
yaux = (1 + j * j / 110 * (-1 + j * j / 156 * (1 + j * j / 210 * yaux2)))
y = j * (1 + j * j / 6 * (-1 + j * j / 20 * (1 + j * j / 42 * (-1 + j * j / 72 * yaux))))
IF y < .01 AND y > -.01 AND ABS(x - pi) < 1 THEN PRINT "PI aprox. = "; x
'PRINT 3.14159265358979# + y
'END
IF ABS(dy * coef < 240) THEN PSET (f, 240 - (dy * coef)), 4

IF (ABS(y * coef) < 240) THEN PSET (f, 240 - (y * coef)), c4




GOTO 5

REM ****** si hay division por 0, etc dibuja la asintota ****************
10 kk = k: k = INT(f): IF k = kk THEN GOTO 11:  ELSE l = -l: IF l = 1 THEN LINE (k, 0)-(k, 479), c3, , &H5555:  ELSE LINE (k, 1)-(k, 479), c3, , &H5555
'PRINT ERL
11 RESUME 5