Recursion: 4 ways to get it working

Recursion: 4 ways to get it working - Printable Version

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RE: Recursion: 4 ways to get it working - Ikerkaz - 02-17-2023

In order to talk about recursion, first you have to talk about recursion Big Grin

RE: Recursion: 4 ways to get it working - bplus - 02-17-2023

@TempodiBasic "Chess Pattern" Looks good!

RE: Recursion: 4 ways to get it working - bplus - 02-17-2023

(02-17-2023, 12:10 PM)Ikerkaz Wrote: In order to talk about recursion, first you have to talk about recursion

Then you have to know when to quit! Smile

RE: Recursion: 4 ways to get it working - bplus - 02-17-2023

Here is a Checkerboard fresh from my brain and QB64 IDE:

Code: (Select All)
_Title "Checkerboard by recursion" ' b+ 2023-02-17

' 8 X 80 = 640

Screen _NewImage(640, 640, 12) ' use 16 QB colors

Check 1, 1

Sleep

Sub Check (x, y)

    If (y Mod 2) Then

        If x Mod 2 Then c = 4 Else c = 0

    Else

        If x Mod 2 Then c = 0 Else c = 4

    End If

    Line ((x - 1) * 80, (y - 1) * 80)-Step(80, 80), c, BF

    Line ((x - 1) * 80, (y - 1) * 80)-Step(79, 79), 14, B

    x = x + 1

    If x > 8 Then y = y + 1: x = 1

    If y > 8 Then

        Exit Sub

    Else

        Check x, y

    End If

End Sub

RE: Recursion: 4 ways to get it working - dcromley - 02-17-2023

Nice patterns. Nice checkerboard. Amazing what can be done in a few lines of code.

I like this -- having the program show what's going on with recursion:

Code: (Select All)
_Title "Recursion Demo" ' dcromley

Screen _NewImage(1024, 768, 12)

Color 0, 15

Cls

Print Chr$(13) + "Finally, factorial(5)=" + Str$(factorial(5))

Function factorial (n)

  Dim t ' t exists for the duration of THIS level of recursion

  Print "Getting factorial(" + Str$(n) + ")"

  If n = 1 Then

    Print "factorial(1) = 1"

    factorial = 1

  Else

    Print "Need factorial(" + Str$(n - 1) + ")"

    t = factorial(n - 1)

    Print "Got factorial(" + Str$(n - 1) + ") =" + Str$(t)

    factorial = n * t

  End If

End Function

RE: Recursion: 4 ways to get it working - TempodiBasic - 02-18-2023

@Bplus
Yes the old color scheme is very fashinating and so the the yellow border!

Here a screeenshot of our different chessboard

[Image: immagine-2023-02-18-101926240.png]

@dcromley
nice output about timing of phases of recursion

RE: Recursion: 4 ways to get it working - TempodiBasic - 02-18-2023

here another simple example of recursion in tail for draw a circle

Code: (Select All)
_Title "Circle by recursion demo"

Screen _NewImage(1000, 1000, 32)

Randomize Timer

_ScreenMove 1, 1

Const Tail = 2, Head = 1

Dim Radius As Integer, centerX As Integer, centerY As Integer, Mode As Integer

Radius = 50

centerX = 500

centerY = 500

Mode = Tail

While InKey$ <> " "

    Locate 1, 1: Print "press spacebar to quit"

    Radius = Radius + 5

    colo~& = _RGB32((Rnd * 255) + 1, (Rnd * 255) + 1, (Rnd * 255) + 1)

    DrawPoint colo~&, 1, CInt(Sin(1) * 100), CInt(Cos(1) * 100), centerX, centerY, Radius

    _Limit 10

Wend

End

Sub DrawPoint (c~&, Sec As Single, Px As Integer, Py As Integer, Cx As Integer, Cy As Integer, Radius As Integer)

    If Sec < 360 Then Sec = Sec + 1 Else Exit Sub

    PSet (Cx, Cy), c~&

    PSet (Px + Cx, Py + Cy), c~&

    Px = CInt(Sin(Sec) * Radius)

    Py = CInt(Cos(Sec) * Radius)

    DrawPoint c~&, Sec, Px, Py, Cx, Cy, Radius ' this is an example of recursion in tail

End Sub