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P/+MANDE2

This website contains an archive of files for the Acorn Electron, BBC Micro, Acorn Archimedes, Commodore 16 and Commodore 64 computers, which Dominic Ford has rescued from his private collection of floppy disks and cassettes.

Some of these files were originally commercial releases in the 1980s and 1990s, but they are now widely available online. I assume that copyright over them is no longer being asserted. If you own the copyright and would like files to be removed, please contact me.

Tape/disk: Home » Personal collection » Acorn ADFS disks » Electron_User_Group » EUG_29.ADF
Filename: P/+MANDE2
Read OK:
File size: 0E8E bytes
Load address: 2B204556
Exec address: 444E414D
File contents
560-570    data for the colour arrays (16 colours only)
           the first number gives the colour (0-3) which is plotted
           on the main screen, the second gives the colours for
           the shadow screen, and so on for the others (third =
           main colour, fourth = shadow colour etc...)  The "sea"
           of the mandelbrot is usually black (0,0), blue or white
           (colour selection depends on lines 1320-1410)
           Therefore you can select your preferred colour scheme
           within the colours defined for the mode by changing these
           lines.  You will need 32 numbers for 16 colour
           mode 1, or 72 for 36 colour mode 2.

580        Blank

590-730    This is the clever bit - the Mandelbrot algorithm.
           The idea of the Mandelbrot set is to iterate the
           equation Z = Z^2 + C, where Z is a complex number,
           given by X + iY.  Points which go infinite before
           MI% iterations have been done are plotted in a colour
           from the array, whereas points which have not gone
           infinite are plotted in the "sea" colour (the first
           colour in the array is reserved for the sea, so that
           you can plot a 2-colour picture by *LOADing SHVPIC1
           at &3000 and doing VDU19s to set colours 1,2 and 3
           to the same colour (with 16 colour mode switched off
           with *FX13,4))

           To square a complex number, the X component becomes
           X squared - Y squared (because i is the square root
           of -1), and the Y component becomes 2 * X * Y.
           The complex constant C is added to Z.  C is made up
           of the coordinates of the pixel.  Apologies to the
           those who hate maths!

           The Mandelbrot set is a 'map' of "Julia sets" (plot
           these by changing line 640 to:
           640 I%=0:X1=X:Y1=Y
           and removing the "+ X" or "+ Y" from lines 670 and
           680.  The best Julia sets to plot are found at the
           edge of the "sea" area of the Mandelbrot set.

           HLT is a flag which indicates that the iterated
           complex number Z has gone theoretically infinite
           - a value of X^2+Y^2 of more than 16 is judged to
           be infinite.  an alternative here is to use
           700 HLT=(ABS(X)+ABS(Y)>4)
           which gives a similar effect, except that plotting
           from -4 to +4 on both axes gives a diamond as the
           first-iteration shape, rather than an ovoid.

           I% is the number of iterations performed.  If Z
           has gone infinite, the sea colour (0) is chosen,
           otherwise a number from 1 to 15 (1 to 3 for non-
           shadow-RAM machines).

  N.B.     For the Sea-horse Valley pictures I added lines
           610-620.  These cut out the bottom left corner
           and part of the right hand side respectively.
           Since 600 iterations takes so long to plot, I
           thought that adding two tests to every point
           plotted was an insignificant delay compared to
           the benefit of removing 3/8 of 65536 (=24566)
           points at the full 600 iterations!

           I would advise you to do something similar if
           you intend to plot at more than 100 iterations
           with any significant sea area.

740        Blank

750-790    Calculate the pixel offset - interpolate between
           pixels to give the array of decimal values of
           points to feed into the algorithm.

800        Blank

810-1500   The 16-colour source code.  An explanation of this
           is given separately.

Mark Bellis
118, The Lawns,
Rolleston-on-Dove,
Burton-on-Trent,
Staffs,
DE13 9DE


00000000  0d 35 36 30 2d 35 37 30  20 20 20 20 64 61 74 61  |.560-570    data|
00000010  20 66 6f 72 20 74 68 65  20 63 6f 6c 6f 75 72 20  | for the colour |
00000020  61 72 72 61 79 73 20 28  31 36 20 63 6f 6c 6f 75  |arrays (16 colou|
00000030  72 73 20 6f 6e 6c 79 29  0d 20 20 20 20 20 20 20  |rs only).       |
00000040  20 20 20 20 74 68 65 20  66 69 72 73 74 20 6e 75  |    the first nu|
00000050  6d 62 65 72 20 67 69 76  65 73 20 74 68 65 20 63  |mber gives the c|
00000060  6f 6c 6f 75 72 20 28 30  2d 33 29 20 77 68 69 63  |olour (0-3) whic|
00000070  68 20 69 73 20 70 6c 6f  74 74 65 64 0d 20 20 20  |h is plotted.   |
00000080  20 20 20 20 20 20 20 20  6f 6e 20 74 68 65 20 6d  |        on the m|
00000090  61 69 6e 20 73 63 72 65  65 6e 2c 20 74 68 65 20  |ain screen, the |
000000a0  73 65 63 6f 6e 64 20 67  69 76 65 73 20 74 68 65  |second gives the|
000000b0  20 63 6f 6c 6f 75 72 73  20 66 6f 72 0d 20 20 20  | colours for.   |
000000c0  20 20 20 20 20 20 20 20  74 68 65 20 73 68 61 64  |        the shad|
000000d0  6f 77 20 73 63 72 65 65  6e 2c 20 61 6e 64 20 73  |ow screen, and s|
000000e0  6f 20 6f 6e 20 66 6f 72  20 74 68 65 20 6f 74 68  |o on for the oth|
000000f0  65 72 73 20 28 74 68 69  72 64 20 3d 0d 20 20 20  |ers (third =.   |
00000100  20 20 20 20 20 20 20 20  6d 61 69 6e 20 63 6f 6c  |        main col|
00000110  6f 75 72 2c 20 66 6f 75  72 74 68 20 3d 20 73 68  |our, fourth = sh|
00000120  61 64 6f 77 20 63 6f 6c  6f 75 72 20 65 74 63 2e  |adow colour etc.|
00000130  2e 2e 29 20 20 54 68 65  20 22 73 65 61 22 0d 20  |..)  The "sea". |
00000140  20 20 20 20 20 20 20 20  20 20 6f 66 20 74 68 65  |          of the|
00000150  20 6d 61 6e 64 65 6c 62  72 6f 74 20 69 73 20 75  | mandelbrot is u|
00000160  73 75 61 6c 6c 79 20 62  6c 61 63 6b 20 28 30 2c  |sually black (0,|
00000170  30 29 2c 20 62 6c 75 65  20 6f 72 20 77 68 69 74  |0), blue or whit|
00000180  65 0d 20 20 20 20 20 20  20 20 20 20 20 28 63 6f  |e.           (co|
00000190  6c 6f 75 72 20 73 65 6c  65 63 74 69 6f 6e 20 64  |lour selection d|
000001a0  65 70 65 6e 64 73 20 6f  6e 20 6c 69 6e 65 73 20  |epends on lines |
000001b0  31 33 32 30 2d 31 34 31  30 29 0d 20 20 20 20 20  |1320-1410).     |
000001c0  20 20 20 20 20 20 54 68  65 72 65 66 6f 72 65 20  |      Therefore |
000001d0  79 6f 75 20 63 61 6e 20  73 65 6c 65 63 74 20 79  |you can select y|
000001e0  6f 75 72 20 70 72 65 66  65 72 72 65 64 20 63 6f  |our preferred co|
000001f0  6c 6f 75 72 20 73 63 68  65 6d 65 0d 20 20 20 20  |lour scheme.    |
00000200  20 20 20 20 20 20 20 77  69 74 68 69 6e 20 74 68  |       within th|
00000210  65 20 63 6f 6c 6f 75 72  73 20 64 65 66 69 6e 65  |e colours define|
00000220  64 20 66 6f 72 20 74 68  65 20 6d 6f 64 65 20 62  |d for the mode b|
00000230  79 20 63 68 61 6e 67 69  6e 67 20 74 68 65 73 65  |y changing these|
00000240  0d 20 20 20 20 20 20 20  20 20 20 20 6c 69 6e 65  |.           line|
00000250  73 2e 20 20 59 6f 75 20  77 69 6c 6c 20 6e 65 65  |s.  You will nee|
00000260  64 20 33 32 20 6e 75 6d  62 65 72 73 20 66 6f 72  |d 32 numbers for|
00000270  20 31 36 20 63 6f 6c 6f  75 72 0d 20 20 20 20 20  | 16 colour.     |
00000280  20 20 20 20 20 20 6d 6f  64 65 20 31 2c 20 6f 72  |      mode 1, or|
00000290  20 37 32 20 66 6f 72 20  33 36 20 63 6f 6c 6f 75  | 72 for 36 colou|
000002a0  72 20 6d 6f 64 65 20 32  2e 0d 0d 35 38 30 20 20  |r mode 2...580  |
000002b0  20 20 20 20 20 20 42 6c  61 6e 6b 0d 0d 35 39 30  |      Blank..590|
000002c0  2d 37 33 30 20 20 20 20  54 68 69 73 20 69 73 20  |-730    This is |
000002d0  74 68 65 20 63 6c 65 76  65 72 20 62 69 74 20 2d  |the clever bit -|
000002e0  20 74 68 65 20 4d 61 6e  64 65 6c 62 72 6f 74 20  | the Mandelbrot |
000002f0  61 6c 67 6f 72 69 74 68  6d 2e 0d 20 20 20 20 20  |algorithm..     |
00000300  20 20 20 20 20 20 54 68  65 20 69 64 65 61 20 6f  |      The idea o|
00000310  66 20 74 68 65 20 4d 61  6e 64 65 6c 62 72 6f 74  |f the Mandelbrot|
00000320  20 73 65 74 20 69 73 20  74 6f 20 69 74 65 72 61  | set is to itera|
00000330  74 65 20 74 68 65 0d 20  20 20 20 20 20 20 20 20  |te the.         |
00000340  20 20 65 71 75 61 74 69  6f 6e 20 5a 20 3d 20 5a  |  equation Z = Z|
00000350  5e 32 20 2b 20 43 2c 20  77 68 65 72 65 20 5a 20  |^2 + C, where Z |
00000360  69 73 20 61 20 63 6f 6d  70 6c 65 78 20 6e 75 6d  |is a complex num|
00000370  62 65 72 2c 0d 20 20 20  20 20 20 20 20 20 20 20  |ber,.           |
00000380  67 69 76 65 6e 20 62 79  20 58 20 2b 20 69 59 2e  |given by X + iY.|
00000390  20 20 50 6f 69 6e 74 73  20 77 68 69 63 68 20 67  |  Points which g|
000003a0  6f 20 69 6e 66 69 6e 69  74 65 20 62 65 66 6f 72  |o infinite befor|
000003b0  65 0d 20 20 20 20 20 20  20 20 20 20 20 4d 49 25  |e.           MI%|
000003c0  20 69 74 65 72 61 74 69  6f 6e 73 20 68 61 76 65  | iterations have|
000003d0  20 62 65 65 6e 20 64 6f  6e 65 20 61 72 65 20 70  | been done are p|
000003e0  6c 6f 74 74 65 64 20 69  6e 20 61 20 63 6f 6c 6f  |lotted in a colo|
000003f0  75 72 0d 20 20 20 20 20  20 20 20 20 20 20 66 72  |ur.           fr|
00000400  6f 6d 20 74 68 65 20 61  72 72 61 79 2c 20 77 68  |om the array, wh|
00000410  65 72 65 61 73 20 70 6f  69 6e 74 73 20 77 68 69  |ereas points whi|
00000420  63 68 20 68 61 76 65 20  6e 6f 74 20 67 6f 6e 65  |ch have not gone|
00000430  0d 20 20 20 20 20 20 20  20 20 20 20 69 6e 66 69  |.           infi|
00000440  6e 69 74 65 20 61 72 65  20 70 6c 6f 74 74 65 64  |nite are plotted|
00000450  20 69 6e 20 74 68 65 20  22 73 65 61 22 20 63 6f  | in the "sea" co|
00000460  6c 6f 75 72 20 28 74 68  65 20 66 69 72 73 74 0d  |lour (the first.|
00000470  20 20 20 20 20 20 20 20  20 20 20 63 6f 6c 6f 75  |           colou|
00000480  72 20 69 6e 20 74 68 65  20 61 72 72 61 79 20 69  |r in the array i|
00000490  73 20 72 65 73 65 72 76  65 64 20 66 6f 72 20 74  |s reserved for t|
000004a0  68 65 20 73 65 61 2c 20  73 6f 20 74 68 61 74 0d  |he sea, so that.|
000004b0  20 20 20 20 20 20 20 20  20 20 20 79 6f 75 20 63  |           you c|
000004c0  61 6e 20 70 6c 6f 74 20  61 20 32 2d 63 6f 6c 6f  |an plot a 2-colo|
000004d0  75 72 20 70 69 63 74 75  72 65 20 62 79 20 2a 4c  |ur picture by *L|
000004e0  4f 41 44 69 6e 67 20 53  48 56 50 49 43 31 0d 20  |OADing SHVPIC1. |
000004f0  20 20 20 20 20 20 20 20  20 20 61 74 20 26 33 30  |          at &30|
00000500  30 30 20 61 6e 64 20 64  6f 69 6e 67 20 56 44 55  |00 and doing VDU|
00000510  31 39 73 20 74 6f 20 73  65 74 20 63 6f 6c 6f 75  |19s to set colou|
00000520  72 73 20 31 2c 32 20 61  6e 64 20 33 0d 20 20 20  |rs 1,2 and 3.   |
00000530  20 20 20 20 20 20 20 20  74 6f 20 74 68 65 20 73  |        to the s|
00000540  61 6d 65 20 63 6f 6c 6f  75 72 20 28 77 69 74 68  |ame colour (with|
00000550  20 31 36 20 63 6f 6c 6f  75 72 20 6d 6f 64 65 20  | 16 colour mode |
00000560  73 77 69 74 63 68 65 64  20 6f 66 66 0d 20 20 20  |switched off.   |
00000570  20 20 20 20 20 20 20 20  77 69 74 68 20 2a 46 58  |        with *FX|
00000580  31 33 2c 34 29 29 0d 0d  20 20 20 20 20 20 20 20  |13,4))..        |
00000590  20 20 20 54 6f 20 73 71  75 61 72 65 20 61 20 63  |   To square a c|
000005a0  6f 6d 70 6c 65 78 20 6e  75 6d 62 65 72 2c 20 74  |omplex number, t|
000005b0  68 65 20 58 20 63 6f 6d  70 6f 6e 65 6e 74 20 62  |he X component b|
000005c0  65 63 6f 6d 65 73 0d 20  20 20 20 20 20 20 20 20  |ecomes.         |
000005d0  20 20 58 20 73 71 75 61  72 65 64 20 2d 20 59 20  |  X squared - Y |
000005e0  73 71 75 61 72 65 64 20  28 62 65 63 61 75 73 65  |squared (because|
000005f0  20 69 20 69 73 20 74 68  65 20 73 71 75 61 72 65  | i is the square|
00000600  20 72 6f 6f 74 0d 20 20  20 20 20 20 20 20 20 20  | root.          |
00000610  20 6f 66 20 2d 31 29 2c  20 61 6e 64 20 74 68 65  | of -1), and the|
00000620  20 59 20 63 6f 6d 70 6f  6e 65 6e 74 20 62 65 63  | Y component bec|
00000630  6f 6d 65 73 20 32 20 2a  20 58 20 2a 20 59 2e 0d  |omes 2 * X * Y..|
00000640  20 20 20 20 20 20 20 20  20 20 20 54 68 65 20 63  |           The c|
00000650  6f 6d 70 6c 65 78 20 63  6f 6e 73 74 61 6e 74 20  |omplex constant |
00000660  43 20 69 73 20 61 64 64  65 64 20 74 6f 20 5a 2e  |C is added to Z.|
00000670  20 20 43 20 69 73 20 6d  61 64 65 20 75 70 0d 20  |  C is made up. |
00000680  20 20 20 20 20 20 20 20  20 20 6f 66 20 74 68 65  |          of the|
00000690  20 63 6f 6f 72 64 69 6e  61 74 65 73 20 6f 66 20  | coordinates of |
000006a0  74 68 65 20 70 69 78 65  6c 2e 20 20 41 70 6f 6c  |the pixel.  Apol|
000006b0  6f 67 69 65 73 20 74 6f  20 74 68 65 0d 20 20 20  |ogies to the.   |
000006c0  20 20 20 20 20 20 20 20  74 68 6f 73 65 20 77 68  |        those wh|
000006d0  6f 20 68 61 74 65 20 6d  61 74 68 73 21 0d 0d 20  |o hate maths!.. |
000006e0  20 20 20 20 20 20 20 20  20 20 54 68 65 20 4d 61  |          The Ma|
000006f0  6e 64 65 6c 62 72 6f 74  20 73 65 74 20 69 73 20  |ndelbrot set is |
00000700  61 20 27 6d 61 70 27 20  6f 66 20 22 4a 75 6c 69  |a 'map' of "Juli|
00000710  61 20 73 65 74 73 22 20  28 70 6c 6f 74 0d 20 20  |a sets" (plot.  |
00000720  20 20 20 20 20 20 20 20  20 74 68 65 73 65 20 62  |         these b|
00000730  79 20 63 68 61 6e 67 69  6e 67 20 6c 69 6e 65 20  |y changing line |
00000740  36 34 30 20 74 6f 3a 0d  20 20 20 20 20 20 20 20  |640 to:.        |
00000750  20 20 20 36 34 30 20 49  25 3d 30 3a 58 31 3d 58  |   640 I%=0:X1=X|
00000760  3a 59 31 3d 59 0d 20 20  20 20 20 20 20 20 20 20  |:Y1=Y.          |
00000770  20 61 6e 64 20 72 65 6d  6f 76 69 6e 67 20 74 68  | and removing th|
00000780  65 20 22 2b 20 58 22 20  6f 72 20 22 2b 20 59 22  |e "+ X" or "+ Y"|
00000790  20 66 72 6f 6d 20 6c 69  6e 65 73 20 36 37 30 20  | from lines 670 |
000007a0  61 6e 64 0d 20 20 20 20  20 20 20 20 20 20 20 36  |and.           6|
000007b0  38 30 2e 20 20 54 68 65  20 62 65 73 74 20 4a 75  |80.  The best Ju|
000007c0  6c 69 61 20 73 65 74 73  20 74 6f 20 70 6c 6f 74  |lia sets to plot|
000007d0  20 61 72 65 20 66 6f 75  6e 64 20 61 74 20 74 68  | are found at th|
000007e0  65 0d 20 20 20 20 20 20  20 20 20 20 20 65 64 67  |e.           edg|
000007f0  65 20 6f 66 20 74 68 65  20 22 73 65 61 22 20 61  |e of the "sea" a|
00000800  72 65 61 20 6f 66 20 74  68 65 20 4d 61 6e 64 65  |rea of the Mande|
00000810  6c 62 72 6f 74 20 73 65  74 2e 0d 0d 20 20 20 20  |lbrot set...    |
00000820  20 20 20 20 20 20 20 48  4c 54 20 69 73 20 61 20  |       HLT is a |
00000830  66 6c 61 67 20 77 68 69  63 68 20 69 6e 64 69 63  |flag which indic|
00000840  61 74 65 73 20 74 68 61  74 20 74 68 65 20 69 74  |ates that the it|
00000850  65 72 61 74 65 64 0d 20  20 20 20 20 20 20 20 20  |erated.         |
00000860  20 20 63 6f 6d 70 6c 65  78 20 6e 75 6d 62 65 72  |  complex number|
00000870  20 5a 20 68 61 73 20 67  6f 6e 65 20 74 68 65 6f  | Z has gone theo|
00000880  72 65 74 69 63 61 6c 6c  79 20 69 6e 66 69 6e 69  |retically infini|
00000890  74 65 0d 20 20 20 20 20  20 20 20 20 20 20 2d 20  |te.           - |
000008a0  61 20 76 61 6c 75 65 20  6f 66 20 58 5e 32 2b 59  |a value of X^2+Y|
000008b0  5e 32 20 6f 66 20 6d 6f  72 65 20 74 68 61 6e 20  |^2 of more than |
000008c0  31 36 20 69 73 20 6a 75  64 67 65 64 20 74 6f 0d  |16 is judged to.|
000008d0  20 20 20 20 20 20 20 20  20 20 20 62 65 20 69 6e  |           be in|
000008e0  66 69 6e 69 74 65 2e 20  20 61 6e 20 61 6c 74 65  |finite.  an alte|
000008f0  72 6e 61 74 69 76 65 20  68 65 72 65 20 69 73 20  |rnative here is |
00000900  74 6f 20 75 73 65 0d 20  20 20 20 20 20 20 20 20  |to use.         |
00000910  20 20 37 30 30 20 48 4c  54 3d 28 41 42 53 28 58  |  700 HLT=(ABS(X|
00000920  29 2b 41 42 53 28 59 29  3e 34 29 0d 20 20 20 20  |)+ABS(Y)>4).    |
00000930  20 20 20 20 20 20 20 77  68 69 63 68 20 67 69 76  |       which giv|
00000940  65 73 20 61 20 73 69 6d  69 6c 61 72 20 65 66 66  |es a similar eff|
00000950  65 63 74 2c 20 65 78 63  65 70 74 20 74 68 61 74  |ect, except that|
00000960  20 70 6c 6f 74 74 69 6e  67 0d 20 20 20 20 20 20  | plotting.      |
00000970  20 20 20 20 20 66 72 6f  6d 20 2d 34 20 74 6f 20  |     from -4 to |
00000980  2b 34 20 6f 6e 20 62 6f  74 68 20 61 78 65 73 20  |+4 on both axes |
00000990  67 69 76 65 73 20 61 20  64 69 61 6d 6f 6e 64 20  |gives a diamond |
000009a0  61 73 20 74 68 65 0d 20  20 20 20 20 20 20 20 20  |as the.         |
000009b0  20 20 66 69 72 73 74 2d  69 74 65 72 61 74 69 6f  |  first-iteratio|
000009c0  6e 20 73 68 61 70 65 2c  20 72 61 74 68 65 72 20  |n shape, rather |
000009d0  74 68 61 6e 20 61 6e 20  6f 76 6f 69 64 2e 0d 0d  |than an ovoid...|
000009e0  20 20 20 20 20 20 20 20  20 20 20 49 25 20 69 73  |           I% is|
000009f0  20 74 68 65 20 6e 75 6d  62 65 72 20 6f 66 20 69  | the number of i|
00000a00  74 65 72 61 74 69 6f 6e  73 20 70 65 72 66 6f 72  |terations perfor|
00000a10  6d 65 64 2e 20 20 49 66  20 5a 0d 20 20 20 20 20  |med.  If Z.     |
00000a20  20 20 20 20 20 20 68 61  73 20 67 6f 6e 65 20 69  |      has gone i|
00000a30  6e 66 69 6e 69 74 65 2c  20 74 68 65 20 73 65 61  |nfinite, the sea|
00000a40  20 63 6f 6c 6f 75 72 20  28 30 29 20 69 73 20 63  | colour (0) is c|
00000a50  68 6f 73 65 6e 2c 0d 20  20 20 20 20 20 20 20 20  |hosen,.         |
00000a60  20 20 6f 74 68 65 72 77  69 73 65 20 61 20 6e 75  |  otherwise a nu|
00000a70  6d 62 65 72 20 66 72 6f  6d 20 31 20 74 6f 20 31  |mber from 1 to 1|
00000a80  35 20 28 31 20 74 6f 20  33 20 66 6f 72 20 6e 6f  |5 (1 to 3 for no|
00000a90  6e 2d 0d 20 20 20 20 20  20 20 20 20 20 20 73 68  |n-.           sh|
00000aa0  61 64 6f 77 2d 52 41 4d  20 6d 61 63 68 69 6e 65  |adow-RAM machine|
00000ab0  73 29 2e 0d 0d 20 20 4e  2e 42 2e 20 20 20 20 20  |s)...  N.B.     |
00000ac0  46 6f 72 20 74 68 65 20  53 65 61 2d 68 6f 72 73  |For the Sea-hors|
00000ad0  65 20 56 61 6c 6c 65 79  20 70 69 63 74 75 72 65  |e Valley picture|
00000ae0  73 20 49 20 61 64 64 65  64 20 6c 69 6e 65 73 0d  |s I added lines.|
00000af0  20 20 20 20 20 20 20 20  20 20 20 36 31 30 2d 36  |           610-6|
00000b00  32 30 2e 20 20 54 68 65  73 65 20 63 75 74 20 6f  |20.  These cut o|
00000b10  75 74 20 74 68 65 20 62  6f 74 74 6f 6d 20 6c 65  |ut the bottom le|
00000b20  66 74 20 63 6f 72 6e 65  72 0d 20 20 20 20 20 20  |ft corner.      |
00000b30  20 20 20 20 20 61 6e 64  20 70 61 72 74 20 6f 66  |     and part of|
00000b40  20 74 68 65 20 72 69 67  68 74 20 68 61 6e 64 20  | the right hand |
00000b50  73 69 64 65 20 72 65 73  70 65 63 74 69 76 65 6c  |side respectivel|
00000b60  79 2e 0d 20 20 20 20 20  20 20 20 20 20 20 53 69  |y..           Si|
00000b70  6e 63 65 20 36 30 30 20  69 74 65 72 61 74 69 6f  |nce 600 iteratio|
00000b80  6e 73 20 74 61 6b 65 73  20 73 6f 20 6c 6f 6e 67  |ns takes so long|
00000b90  20 74 6f 20 70 6c 6f 74  2c 20 49 0d 20 20 20 20  | to plot, I.    |
00000ba0  20 20 20 20 20 20 20 74  68 6f 75 67 68 74 20 74  |       thought t|
00000bb0  68 61 74 20 61 64 64 69  6e 67 20 74 77 6f 20 74  |hat adding two t|
00000bc0  65 73 74 73 20 74 6f 20  65 76 65 72 79 20 70 6f  |ests to every po|
00000bd0  69 6e 74 0d 20 20 20 20  20 20 20 20 20 20 20 70  |int.           p|
00000be0  6c 6f 74 74 65 64 20 77  61 73 20 61 6e 20 69 6e  |lotted was an in|
00000bf0  73 69 67 6e 69 66 69 63  61 6e 74 20 64 65 6c 61  |significant dela|
00000c00  79 20 63 6f 6d 70 61 72  65 64 20 74 6f 0d 20 20  |y compared to.  |
00000c10  20 20 20 20 20 20 20 20  20 74 68 65 20 62 65 6e  |         the ben|
00000c20  65 66 69 74 20 6f 66 20  72 65 6d 6f 76 69 6e 67  |efit of removing|
00000c30  20 33 2f 38 20 6f 66 20  36 35 35 33 36 20 28 3d  | 3/8 of 65536 (=|
00000c40  32 34 35 36 36 29 0d 20  20 20 20 20 20 20 20 20  |24566).         |
00000c50  20 20 70 6f 69 6e 74 73  20 61 74 20 74 68 65 20  |  points at the |
00000c60  66 75 6c 6c 20 36 30 30  20 69 74 65 72 61 74 69  |full 600 iterati|
00000c70  6f 6e 73 21 0d 0d 20 20  20 20 20 20 20 20 20 20  |ons!..          |
00000c80  20 49 20 77 6f 75 6c 64  20 61 64 76 69 73 65 20  | I would advise |
00000c90  79 6f 75 20 74 6f 20 64  6f 20 73 6f 6d 65 74 68  |you to do someth|
00000ca0  69 6e 67 20 73 69 6d 69  6c 61 72 20 69 66 0d 20  |ing similar if. |
00000cb0  20 20 20 20 20 20 20 20  20 20 79 6f 75 20 69 6e  |          you in|
00000cc0  74 65 6e 64 20 74 6f 20  70 6c 6f 74 20 61 74 20  |tend to plot at |
00000cd0  6d 6f 72 65 20 74 68 61  6e 20 31 30 30 20 69 74  |more than 100 it|
00000ce0  65 72 61 74 69 6f 6e 73  0d 20 20 20 20 20 20 20  |erations.       |
00000cf0  20 20 20 20 77 69 74 68  20 61 6e 79 20 73 69 67  |    with any sig|
00000d00  6e 69 66 69 63 61 6e 74  20 73 65 61 20 61 72 65  |nificant sea are|
00000d10  61 2e 0d 0d 37 34 30 20  20 20 20 20 20 20 20 42  |a...740        B|
00000d20  6c 61 6e 6b 0d 0d 37 35  30 2d 37 39 30 20 20 20  |lank..750-790   |
00000d30  20 43 61 6c 63 75 6c 61  74 65 20 74 68 65 20 70  | Calculate the p|
00000d40  69 78 65 6c 20 6f 66 66  73 65 74 20 2d 20 69 6e  |ixel offset - in|
00000d50  74 65 72 70 6f 6c 61 74  65 20 62 65 74 77 65 65  |terpolate betwee|
00000d60  6e 0d 20 20 20 20 20 20  20 20 20 20 20 70 69 78  |n.           pix|
00000d70  65 6c 73 20 74 6f 20 67  69 76 65 20 74 68 65 20  |els to give the |
00000d80  61 72 72 61 79 20 6f 66  20 64 65 63 69 6d 61 6c  |array of decimal|
00000d90  20 76 61 6c 75 65 73 20  6f 66 0d 20 20 20 20 20  | values of.     |
00000da0  20 20 20 20 20 20 70 6f  69 6e 74 73 20 74 6f 20  |      points to |
00000db0  66 65 65 64 20 69 6e 74  6f 20 74 68 65 20 61 6c  |feed into the al|
00000dc0  67 6f 72 69 74 68 6d 2e  0d 0d 38 30 30 20 20 20  |gorithm...800   |
00000dd0  20 20 20 20 20 42 6c 61  6e 6b 0d 0d 38 31 30 2d  |     Blank..810-|
00000de0  31 35 30 30 20 20 20 54  68 65 20 31 36 2d 63 6f  |1500   The 16-co|
00000df0  6c 6f 75 72 20 73 6f 75  72 63 65 20 63 6f 64 65  |lour source code|
00000e00  2e 20 20 41 6e 20 65 78  70 6c 61 6e 61 74 69 6f  |.  An explanatio|
00000e10  6e 20 6f 66 20 74 68 69  73 0d 20 20 20 20 20 20  |n of this.      |
00000e20  20 20 20 20 20 69 73 20  67 69 76 65 6e 20 73 65  |     is given se|
00000e30  70 61 72 61 74 65 6c 79  2e 0d 0d 4d 61 72 6b 20  |parately...Mark |
00000e40  42 65 6c 6c 69 73 0d 31  31 38 2c 20 54 68 65 20  |Bellis.118, The |
00000e50  4c 61 77 6e 73 2c 0d 52  6f 6c 6c 65 73 74 6f 6e  |Lawns,.Rolleston|
00000e60  2d 6f 6e 2d 44 6f 76 65  2c 0d 42 75 72 74 6f 6e  |-on-Dove,.Burton|
00000e70  2d 6f 6e 2d 54 72 65 6e  74 2c 0d 53 74 61 66 66  |-on-Trent,.Staff|
00000e80  73 2c 0d 44 45 31 33 20  39 44 45 0d 0d 0d        |s,.DE13 9DE...|
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