Source code in the basic programming language

maxIt = 13 : maxItj = 13
a1 = 1.0 : a2 = 0.0 : d = 0.0 : d1 = 3.2

print "Feigenbaum constant calculation:"
print
print "  i      d"
print "======================"

for i = 2 to maxIt
    a = a1 + (a1 - a2) / d1
    for j = 1 to maxItj
        x = 0.0 : y = 0.0
        for k = 1 to 2 ^ i
            y = 1 - 2 * y * x
            x = a - x * x
        next k
        a -= x / y
    next j
    d = (a1 - a2) / (a - a1)
    print rjust(i,3); chr(9); ljust(d,13,"0")
    d1 = d
    a2 = a1
    a1 = a
next i

100 cls
110 mit = 13
120 mitj = 13
130 a1 = 1
140 a2 = 0
150 d = 0
160 d1 = 3.2
170 print "Feigenbaum constant calculation:"
180 print
190 print "  i     d"
200 print "==================="
210 for i = 2 to mit
220   a = a1+(a1-a2)/d1
230   for j = 1 to mitj
240     x = 0
250     y = 0
260     for k = 1 to 2^i
270       y = 1-2*y*x
280       x = a-x*x
290     next k
300     a = a-(x/y)
310   next j
320   d = (a1-a2)/(a-a1)
330   print using "###";i;"    ";
335   print using "##.#########";d
340   d1 = d
350   a2 = a1
360   a1 = a
370 next i
380 end


maxit = 13 : maxitj = 13
a1 = 1.0 : a2 = 0.0 : d = 0.0 : d1 = 3.2

print "Feigenbaum constant calculation:"
print
print "  i     d"
print "==================="

for i = 2 to maxit
  a = a1 + (a1 - a2) / d1
  for j = 1 to maxitj
    x = 0 : y = 0
    for k = 1 to 2 ^ i
      y = 1 - 2 * y * x
      x = a - x * x
    next k
    a = a - (x / y)
  next j
  d = (a1 - a2) / (a - a1)
  print i; tab(8); d
  d1 = d
  a2 = a1
  a1 = a
next i

100 CLS
110 mit = 13
120 mitj = 13
130 a1 = 1
140 a2 = 0
150 d = 0
160 d1 = 3.2
170 PRINT "Feigenbaum constant calculation:"
180 PRINT
190 PRINT "  i     d"
200 PRINT "==================="
210 FOR i = 2 TO mit
220   a = a1 + (a1 - a2) / d1
230   FOR j = 1 TO mitj
240     x = 0
250     y = 0
260     FOR k = 1 TO 2 ^ i
270       y = 1 - 2 * y * x
280       x = a - x * x
290     NEXT k
300     a = a - (x / y)
310   NEXT j
320   d = (a1 - a2) / (a - a1)
330   PRINT USING "###    ##.#########"; i; d
340   d1 = d
350   a2 = a1
360   a1 = a
370 NEXT i
380 END


LET maxit = 13
LET maxitj = 13
LET a1 = 1.0
LET d1 = 3.2

PRINT "Feigenbaum constant calculation:"
PRINT
PRINT "  i     d"
PRINT "==================="

FOR i = 2 to maxit
    LET a = a1 + (a1 - a2) / d1
    FOR j = 1 to maxitj
        LET x = 0
        LET y = 0
        FOR k = 1 to 2 ^ i
            LET y = 1 - 2 * y * x
            LET x = a - x * x
        NEXT k
        LET a = a - (x / y)
    NEXT j
    LET d = (a1 - a2) / (a - a1)
    PRINT using "###    ##.#########": i, d
    LET d1 = d
    LET a2 = a1
    LET a1= a
NEXT i
END


maxIt = 13 : maxItj = 13
a1 = 1.0 : a2 = 0.0 : d = 0.0 : d1 = 3.2

print "Feigenbaum constant calculation:"
print "\n  i      d"
print "===================="

for i = 2 to maxIt
    a = a1 + (a1 - a2) / d1
    for j = 1 to maxItj
        x = 0.0 : y = 0.0
        for k = 1 to 2 ^ i
            y = 1 - 2 * y * x
            x = a - x * x
        next k
        a = a - x / y
    next j
    d = (a1 - a2) / (a - a1)
    print i using("###"), chr$(9), d
    d1 = d
    a2 = a1
    a1 = a
next i