It's high time for the second installment of stupid coding tricks! As we learned from the T-SQL Mandelbrot, a stupid coding trick isn't really about obfuscation per se... just, well, stupid awesomeness. Kinda like a quine, except even more useless.

Don Cross was gracious enough to provide today's example, which teeters on the edge of what many consider "code". It's a Win32 batch file. Unlike the analogous *nix shell script, batch "programming" comes with an incredibly limited syntax and a miniscule number of commands. While one can certainly do far more in batch than ever should be done, the technology works well foa shortcut for typing in a bunch of commands.

In fact, the programmability of batch is so limited that discovering the ability to perform "simple arithmetic on 32-bit signed integers" is worthy of a blog post. In fact, when I first read that post from Raymond, I remember thinking, hey sweet, more functionality in batch; so... now I can do... err....what?

Well, now I can finally answer that question. Submitted for your approval: pi.bat, a high-precision pi calculator that uses entirely batch commands.

@if defined talk (echo on) else (echo off) setlocal EnableDelayedExpansion echo.pi.bat - By Don Cross - http://cosinekitty.com set /a NumQuads = 30 set /a MaxQuadIndex = NumQuads - 1 echo. echo.%time% - started echo. call :PiEngine 48 18 32 57 -20 239 call :PiEngine 16 5 -4 239 goto :EOF :PiEngine call :SetToInteger Pi 0 set Formula= :PiTermLoop if "%1" == "" ( call :Print pi echo. echo.!time! - finished !Formula! echo. goto :EOF ) call :ArctanRecip PiTerm %2 set /a PiEngineFactor=%1 if !PiEngineFactor! lss 0 ( set /a PiEngineFactor *= -1 set Formula=!Formula! call :MultiplyByInteger PiTerm !PiEngineFactor! call :Subtract Pi PiTerm set Operator=- ) else ( call :MultiplyByInteger PiTerm %1 call :Add Pi PiTerm set Operator=+ ) if defined Formula ( set Formula=!Formula! !Operator! !PiEngineFactor!*arctan^(1/%2^) ) else ( set Formula=pi = %1*arctan^(1/%2^) ) shift shift goto PiTermLoop :SetToInteger for /L %%i in (0, 1, !MaxQuadIndex!) do ( set /a %1_%%i = 0 ) set /a %1_!MaxQuadIndex! = %2 goto :EOF :Print set PrintBuffer=x REM Omit a couple of least significant quads, because they will have roundoff errors. if defined PiDebug ( set /a PrintMinQuadIndex=0 ) else ( set /a PrintMinQuadIndex=2 ) set /a PrintMaxQuadIndex = MaxQuadIndex - 1 for /L %%i in (!PrintMinQuadIndex!, 1, !PrintMaxQuadIndex!) do ( set PrintDigit=!%1_%%i! if !PrintDigit! lss 1000 ( if !PrintDigit! lss 100 ( if !PrintDigit! lss 10 ( set PrintDigit=000!PrintDigit! ) else ( set PrintDigit=00!PrintDigit! ) ) else ( set PrintDigit=0!PrintDigit! ) ) set PrintBuffer=!PrintDigit!!PrintBuffer! ) set PrintBuffer=!%1_%MaxQuadIndex%!.!PrintBuffer:x=! echo.%1 = !PrintBuffer! goto :EOF :DivideByInteger if defined PiDebug echo.DivideByInteger %1 %2 set /a DBI_Carry = 0 for /L %%i in (!MaxQuadIndex!, -1, 0) do ( set /a DBI_Digit = DBI_Carry*10000 + %1_%%i set /a DBI_Carry = DBI_Digit %% %2 set /a %1_%%i = DBI_Digit / %2 ) goto :EOF :MultiplyByInteger if defined PiDebug echo.MultiplyByInteger %1 %2 set /a MBI_Carry = 0 for /L %%i in (0, 1, !MaxQuadIndex!) do ( set /a MBI_Digit = %1_%%i * %2 + MBI_Carry set /a %1_%%i = MBI_Digit %% 10000 set /a MBI_Carry = MBI_Digit / 10000 ) goto :EOF :ArctanRecip if defined PiDebug echo.ArctanRecip %1 %2 call :SetToInteger %1 1 call :DivideByInteger %1 %2 call :CopyValue AR_Recip %1 set /a AR_Toggle = -1 set /a AR_K = 3 :ArctanLoop if defined PiDebug ( echo. echo.ArctanRecip AR_K=!AR_K! --------------------------------------------------------- ) call :DivideByInteger AR_Recip %2 call :DivideByInteger AR_Recip %2 call :CopyValue AR_Term AR_Recip call :DivideByInteger AR_Term !AR_K! call :CopyValue AR_PrevSum %1 if !AR_Toggle! lss 0 ( call :Subtract %1 AR_Term ) else ( call :Add %1 AR_Term ) call :Compare AR_EqualFlag %1 AR_PrevSum if !AR_EqualFlag! == true goto :EOF set /a AR_K += 2 set /a AR_Toggle *= -1 goto ArctanLoop :CopyValue if defined PiDebug echo.CopyValue %1 %2 for /L %%i in (0, 1, !MaxQuadIndex!) do ( set /a %1_%%i = %2_%%i ) goto :EOF :Add if defined PiDebug echo.Add %1 %2 if defined PiDebug call :Print %1 if defined PiDebug call :Print %2 set /a Add_Carry = 0 for /L %%i in (0, 1, !MaxQuadIndex!) do ( set /a Add_Digit = Add_Carry + %1_%%i + %2_%%i set /a %1_%%i = Add_Digit %% 10000 set /a Add_Carry = Add_Digit / 10000 ) goto :EOF :Subtract if defined PiDebug echo.Subtract %1 %2 if defined PiDebug call :Print %1 if defined PiDebug call :Print %2 set /a Subtract_Borrow = 0 for /L %%i in (0, 1, !MaxQuadIndex!) do ( set /a Subtract_Digit = %1_%%i - %2_%%i - Subtract_Borrow if !Subtract_Digit! lss 0 ( set /a Subtract_Digit += 10000 set /a Subtract_Borrow = 1 ) else ( set /a Subtract_Borrow = 0 ) set /a %1_%%i = Subtract_Digit ) goto :EOF :Compare if defined PiDebug echo.Compare %1 %2 %3 if defined PiDebug call :Print %2 if defined PiDebug call :Print %3 set /a Compare_Index = 0 set %1=true :CompareLoop if not !%2_%Compare_Index%! == !%3_%Compare_Index%! ( if defined PiDebug echo.!%2_%Compare_Index%! neq !%3_%Compare_Index%! set %1=false goto :EOF ) set /a Compare_Index += 1 if !Compare_Index! gtr !MaxQuadIndex! ( if defined PiDebug echo.Compare equal goto :EOF ) goto CompareLoop REM $Log: pi.bat,v $ REM Revision 1.2 2007/09/06 21:49:15 Don.Cross REM Added time stamps and display of formula. REM REM Revision 1.1 2007/09/06 21:12:36 Don.Cross REM Batch file for calculating pi REM

As for the output, here's what came up when I ran it on my machine.

> pi pi.bat - By Don Cross - http://cosinekitty.com 1:42:47.79 - started pi = 3.1415926535897932384626433832795028841971693993751058209749445923078164062 86208998628034825342117067982148086 1:43:07.36 - finished pi = 48*arctan(1/18) + 32*arctan(1/57) - 20*arctan(1/239) pi = 3.1415926535897932384626433832795028841971693993751058209749445923078164062 86208998628034825342117067982148086 1:43:27.26 - finished pi = 16*arctan(1/5) - 4*arctan(1/239)

Got a stupid coding trick of your own? Well then send it on in!