Author Topic: Simulating Addition/Subtraction/Multiplication/Division via strings (Read 4593 times)

Sanmayce · « **on:** June 19, 2021, 01:15:15 am »

Hi,
just saw several fellow members interested in arithmeticity, :P

I wrote this string library back in nineties, it works, as for speed - it was benchmarked successfully on ... 8086, eh. Enjoy!

Code: QB64: [Select]

' RTHMTC.TMR - simulating the four arithmetic operations via strings, written back in 90's by Kaze, (sanmayce[member=743]Sanmayce[/member].com)
 
'DECLARE SUB DelNull (Result%(), Tiller$, DimLength%)
'DECLARE SUB DelLeftNull (Result%(), Tiller$, StrLength%, DimLength%, PointPos%)
'DECLARE SUB DelRightNull (Result%(), Tiller$, StrLength%, PointPos%)
'DECLARE SUB Convert (Array%(), Number$, Length%, Flag%, PointPos%)
'DECLARE FUNCTION FindIntegerPart$ (Dividend$, Divisor$)
'DECLARE FUNCTION DIV$ (Dividend$, Divisor$, Exactness%)
'DECLARE FUNCTION ADD$ (FirstAddend$, SecondAddend$)
'DECLARE FUNCTION SUBqb$ (Minuend$, Subtrahend$)
'DECLARE FUNCTION MUL$ (Multiplicand$, Multiplier$)
'DECLARE FUNCTION Compare% (Firum$, Secum$)
'DECLARE FUNCTION ResultFilter$ (Result%(), Code$, DimLength%, PointPos%, Sign%)
 
' Examples [
PRINT ADD$("123.89", "3")
PRINT SUBqb$("-3", "3")
PRINT MUL$("-0.4", "222222222222222222222222222222222222")
PRINT DIV$("22.7", "-3", 10)
' Examples ]
 
DEFINT A-Z
FUNCTION ADD$ (FirstAddend$, SecondAddend$)
    FiradLength = LEN(FirstAddend$)
    SecadLength = LEN(SecondAddend$)
    FirstSign$ = MID$(FirstAddend$, 1, 1)
    SecondSign$ = MID$(SecondAddend$, 1, 1)
    IF FirstSign$ <> "-" AND SecondSign$ = "-" THEN
        Mediator$ = RIGHT$(SecondAddend$, SecadLength - 1)
        ADD$ = SUBqb$(FirstAddend$, Mediator$)
        EXIT FUNCTION
    END IF
    IF FirstSign$ = "-" AND SecondSign$ <> "-" THEN
        Mediator$ = RIGHT$(FirstAddend$, FiradLength - 1)
        ADD$ = SUBqb$(SecondAddend$, Mediator$)
        EXIT FUNCTION
    END IF
    IF FirstSign$ = "-" AND SecondSign$ = "-" THEN
        Sign = 1
        FiradLength = FiradLength - 1
        SecadLength = SecadLength - 1
        FirstAddend$ = RIGHT$(FirstAddend$, FiradLength)
        SecondAddend$ = RIGHT$(SecondAddend$, SecadLength)
    END IF
    REDIM Firad%(1 TO FiradLength)
    REDIM Secad%(1 TO SecadLength)
    CALL Convert(Firad%(), FirstAddend$, FiradLength, FiradFlag, FiradPointPos)
    FiradTrueLength = FiradLength - FiradPointPos
    CALL Convert(Secad%(), SecondAddend$, SecadLength, SecadFlag, SecadPointPos)
    SecadTrueLength = SecadLength - SecadPointPos
    IF SecadTrueLength > FiradTrueLength THEN
        BigLength = SecadTrueLength
    ELSE
        BigLength = FiradTrueLength
    END IF
    IF FiradPointPos > SecadPointPos THEN
        BigPointPos = FiradPointPos
        TrueBigPointPos = BigPointPos - FiradFlag
        SubSecad = SecadPointPos - SecadFlag - TrueBigPointPos
    ELSE
        BigPointPos = SecadPointPos
        TrueBigPointPos = BigPointPos - SecadFlag
        SubFirad = FiradPointPos - FiradFlag - TrueBigPointPos
    END IF
    DimSum = BigLength + TrueBigPointPos + 1
    REDIM Result%(1 TO DimSum)
    FOR SF = 1 TO BigLength + BigPointPos
        FiradDim = 0
        SecadDim = 0
        SubFirad = SubFirad + 1
        SubSecad = SubSecad + 1
        IF SubFirad > 0 AND SubFirad <= FiradLength THEN FiradDim = Firad%(SubFirad)
        IF SubSecad > 0 AND SubSecad <= SecadLength THEN SecadDim = Secad%(SubSecad)
        Result%(SF) = FiradDim + SecadDim + Result%(SF)
        IF Result%(SF) >= 10 THEN
            Result%(SF + 1) = 1
            Result%(SF) = Result(SF) - 10
        END IF
    NEXT SF
    ADD$ = ResultFilter$(Result%(), "ADD", DimSum, BigPointPos, Sign)
END FUNCTION
 
FUNCTION Compare% (Firum$, Secum$)
    FirLeftPart = INSTR(Firum$, ".")
    SecLeftPart = INSTR(Secum$, ".")
    IF FirLeftPart = 0 THEN
        FirLeftPart = LEN(Firum$)
    ELSE
        FirLeftPart = FirLeftPart - 1
        FirRightPart = LEN(Firum$) - FirLeftPart
    END IF
    IF SecLeftPart = 0 THEN
        SecLeftPart = LEN(Secum$)
    ELSE
        SecLeftPart = SecLeftPart - 1
        SecRightPart = LEN(Secum$) - SecLeftPart
    END IF
    IF SecRightPart > FirRightPart THEN
        MainRightPart = FirRightPart
    ELSE
        MainRightPart = SecRightPart
    END IF
    IF SecLeftPart > FirLeftPart THEN
        CompareCode = -1
        MainLeftPart = SecLeftPart
    ELSE
        CompareCode = 1
        MainLeftPart = FirLeftPart
    END IF
    IF SecLeftPart = FirLeftPart THEN
        CompareCode = 0
        DO
            Counter = Counter + 1
            FirumPart = VAL(MID$(Firum$, Counter, 1))
            SecumPart = VAL(MID$(Secum$, Counter, 1))
            IF FirumPart > SecumPart THEN CompareCode = 1
            IF FirumPart < SecumPart THEN CompareCode = -1
        LOOP WHILE Counter < MainLeftPart AND FirumPart = SecumPart
        IF CompareCode = 0 THEN
            MainLength = MainLeftPart + MainRightPart
            IF MainRightPart > 0 THEN
                Counter = Counter + 1
                DO
                    Counter = Counter + 1
                    FirumPart = VAL(MID$(Firum$, Counter, 1))
                    SecumPart = VAL(MID$(Secum$, Counter, 1))
                    IF FirumPart > SecumPart THEN CycleFlag = 1: CompareCode = 1
                    IF FirumPart < SecumPart THEN CycleFlag = 1: CompareCode = -1
                LOOP WHILE Counter < MainLength AND FirumPart = SecumPart
            END IF
            IF Counter = MainLength AND CycleFlag = 0 THEN
                IF FirRightPart < SecRightPart THEN CompareCode = -1
                IF FirRightPart > SecRightPart THEN CompareCode = 1
            END IF
        END IF
    END IF
    Compare% = CompareCode
END FUNCTION
 
SUB Convert (Array%(), Number$, Length, Flag, PointPos)
    FOR Counter = 1 TO Length
        Shoot$ = MID$(Number$, Length - Counter + 1, 1)
        IF Shoot$ = "." THEN
            Flag = 1
            PointPos = Counter
            Counter = Counter + 1
            Shoot$ = MID$(Number$, Length - Counter + 1, 1)
        END IF
        Array%(Counter - Flag) = VAL(Shoot$)
    NEXT Counter
END SUB
 
SUB DelLeftNull (Result%(), Tiller$, StrLength, DimLength, PointPos)
    Counter = DimLength
    DeviPart = DimLength + 1 - StrLength
    DO WHILE PointPos + 1 <= Counter - DeviPart AND Result%(Counter) = 0
        StrLength = StrLength - 1
        Tiller$ = RIGHT$(Tiller$, StrLength)
        Counter = Counter - 1
    LOOP
END SUB
 
SUB DelNull (Result%(), Tiller$, DimLength)
    Counter = DimLength
    DO WHILE Result%(Counter) = 0 AND Counter >= 2
        Tiller$ = RIGHT$(Tiller$, Counter - 1)
        Counter = Counter - 1
    LOOP
END SUB
 
SUB DelRightNull (Result%(), Tiller$, StrLength, PointPos)
    Counter = 1
    NewPointPos = PointPos
    DO WHILE PointPos - 2 >= Counter AND Result%(Counter) = 0
        StrLength = StrLength - 1
        Tiller$ = LEFT$(Tiller$, StrLength)
        Counter = Counter + 1
        NewPointPos = NewPointPos - 1
    LOOP
    PointPos = NewPointPos
END SUB
 
FUNCTION DIV$ (Dividend$, Divisor$, Exactness)
    DendSign$ = MID$(Dividend$, 1, 1)
    SorSign$ = MID$(Divisor$, 1, 1)
    IF DendSign$ = "-" AND SorSign$ <> "-" THEN
        Sign = 1
        Dividend$ = RIGHT$(Dividend$, LEN(Dividend$) - 1)
    END IF
    IF DendSign$ <> "-" AND SorSign$ = "-" THEN
        Sign = 1
        Divisor$ = RIGHT$(Divisor$, LEN(Divisor$) - 1)
    END IF
    IF DendSign$ = "-" AND SorSign$ = "-" THEN
        Divisor$ = RIGHT$(Divisor$, LEN(Divisor$) - 1)
        Dividend$ = RIGHT$(Dividend$, LEN(Dividend$) - 1)
    END IF
    DendPointPos = INSTR(Dividend$, ".")
    SorPointPos = INSTR(Divisor$, ".")
    IF DendPointPos <> 0 THEN
        DendRightPart = LEN(Dividend$) - DendPointPos
        DendRightPart$ = RIGHT$(Dividend$, DendRightPart)
        Dividend$ = LEFT$(Dividend$, DendPointPos - 1) + DendRightPart$
    END IF
    IF SorPointPos <> 0 THEN
        SorRightPart = LEN(Divisor$) - SorPointPos
        SorRightPart$ = RIGHT$(Divisor$, SorRightPart)
        Divisor$ = LEFT$(Divisor$, SorPointPos - 1) + SorRightPart$
    END IF
    DO WHILE MID$(Dividend$, 1, 1) = "0" AND LEN(Dividend$) <> 1
        Dividend$ = RIGHT$(Dividend$, LEN(Dividend$) - 1)
    LOOP
    DO WHILE MID$(Divisor$, 1, 1) = "0" AND LEN(Divisor$) <> 1
        Divisor$ = RIGHT$(Divisor$, LEN(Divisor$) - 1)
    LOOP
    IF Divisor$ = "0" THEN ERROR 11
    DendLength = LEN(Dividend$)
    SorLength = LEN(Divisor$)
    IF DendLength <= SorLength THEN
        Tiller$ = Dividend$
        Mediator$ = FindIntegerPart$(Dividend$, Divisor$)
        IntegerPart$ = Mediator$
    ELSE
        Pointer = SorLength
        Tiller$ = MID$(Dividend$, 1, Pointer)
        IF FindIntegerPart$(Tiller$, Divisor$) = "0" THEN
            Pointer = SorLength + 1
            Tiller$ = MID$(Dividend$, 1, Pointer)
        END IF
        DO WHILE Pointer < DendLength
            Mediator$ = FindIntegerPart$(Tiller$, Divisor$)
            IntegerPart$ = IntegerPart$ + Mediator$
            Pointer = Pointer + 1
            Shoot$ = MUL$(Mediator$, Divisor$)
            Deviation$ = SUBqb$(Tiller$, Shoot$)
            IF Deviation$ = "0" THEN
                Tiller$ = MID$(Dividend$, Pointer, 1)
            ELSE
                Tiller$ = Deviation$ + MID$(Dividend$, Pointer, 1)
            END IF
        LOOP
        Mediator$ = FindIntegerPart$(Tiller$, Divisor$)
        IntegerPart$ = IntegerPart$ + Mediator$
    END IF
    Result$ = IntegerPart$
    RelativePosition = DendRightPart - SorRightPart
    MiddlePosition = LEN(IntegerPart$) - RelativePosition
    CycleLength = Exactness - RelativePosition
    IF CycleLength > 0 THEN
        FOR I = 1 TO CycleLength
            Shoot$ = MUL$(Mediator$, Divisor$)
            Deviation$ = SUBqb$(Tiller$, Shoot$)
            IF Deviation$ = "0" THEN Tiller$ = "0" ELSE Tiller$ = Deviation$ + "0"
            Mediator$ = FindIntegerPart$(Tiller$, Divisor$)
            FractionalPart$ = FractionalPart$ + Mediator$
        NEXT I
        Result$ = Result$ + FractionalPart$
    END IF
    IF MiddlePosition > 0 THEN
        LeftPart$ = LEFT$(Result$, MiddlePosition)
        IF Exactness = 0 THEN
            Result$ = LeftPart$
        ELSE
            RightPart$ = RIGHT$(Result$, LEN(Result$) - MiddlePosition)
            Result$ = LeftPart$ + "." + RightPart$
        END IF
        IF DendLength <= SorLength THEN
            'Below lines for what captain.
            'NullNumber = SorLength - DendLength + 1 'Bug appears here
            '                                        'because +1 or +0 must.
            'IF MiddlePosition > NullNumber THEN
            'DelLength = NullNumber
            'ELSEIF MiddlePosition = NullNumber THEN
            'DelLength = NullNumber - 1
            'ELSEIF MiddlePosition > 1 THEN
            'DelLength = MiddlePosition - 1
            'END IF
            'Result$ = RIGHT$(Result$, LEN(Result$) - DelLength)
            DO WHILE LEN(Result$) >= 2
                IF LEFT$(Result$, 1) = "0" AND MID$(Result$, 2, 1) <> "." THEN
                    Result$ = RIGHT$(Result$, LEN(Result$) - 1)
                ELSE
                    EXIT DO
                END IF
            LOOP
        END IF
    ELSE
        IF MiddlePosition = 0 THEN
            Result$ = "0." + Result$
        ELSE
            Result$ = "0." + STRING$(ABS(MiddlePosition), "0") + Result$
        END IF
        IF Exactness = 0 THEN
            Result$ = "0"
        ELSEIF CycleLength < 0 THEN
            Result$ = LEFT$(Result$, 2 + Exactness)
        END IF
    END IF
    IF Sign = 1 THEN DIV$ = "-" + Result$ ELSE DIV$ = Result$
END FUNCTION
 
FUNCTION FindIntegerPart$ (Dividend$, Divisor$)
    DO
        Counter = Counter + 1
        Digit$ = LTRIM$(STR$(Counter))
        Tiller$ = MUL$(Digit$, Divisor$)
        CompareCode = Compare%(Tiller$, Dividend$)
    LOOP WHILE Counter <= 9 AND CompareCode = -1
    FindIntegerPart$ = LTRIM$(STR$(Counter - CompareCode))
END FUNCTION
 
FUNCTION MUL$ (Multiplicand$, Multiplier$)
    CandSign$ = MID$(Multiplicand$, 1, 1)
    ErSign$ = MID$(Multiplier$, 1, 1)
    CandLength = LEN(Multiplicand$)
    ErLength = LEN(Multiplier$)
    IF CandSign$ = "-" AND ErSign$ <> "-" THEN
        Sign = 1
        CandLength = CandLength - 1
        Multiplicand$ = RIGHT$(Multiplicand$, CandLength)
    END IF
    IF CandSign$ <> "-" AND ErSign$ = "-" THEN
        Sign = 1
        ErLength = ErLength - 1
        Multiplier$ = RIGHT$(Multiplier$, ErLength)
    END IF
    IF CandSign$ = "-" AND ErSign$ = "-" THEN
        ErLength = ErLength - 1
        CandLength = CandLength - 1
        Multiplier$ = RIGHT$(Multiplier$, ErLength)
        Multiplicand$ = RIGHT$(Multiplicand$, CandLength)
    END IF
    REDIM Cand%(1 TO CandLength)
    REDIM Er%(1 TO ErLength)
    CALL Convert(Cand%(), Multiplicand$, CandLength, CandFlag, CandPointPos)
    CALL Convert(Er%(), Multiplier$, ErLength, ErFlag, ErPointPos)
    DimSum = CandLength + ErLength - CandFlag - ErFlag
    PointPos = CandPointPos + ErPointPos - CandFlag - ErFlag
    REDIM Result%(1 TO DimSum)
    FOR SF = 1 TO CandLength - CandFlag
        FOR QB = 1 TO ErLength - ErFlag
            CarryFlag = 0
            Cycle = QB - 1 + SF
            Tiller = Cand%(SF) * Er%(QB)
            Result%(Cycle) = Tiller MOD 10 + Result%(Cycle)
            IF Result%(Cycle) >= 10 THEN
                Result%(Cycle) = Result%(Cycle) - 10
                CarryFlag = 1
            END IF
            NextNumPos = Cycle + 1
            Result%(NextNumPos) = Result%(NextNumPos) + CarryFlag + Tiller \ 10
            DO WHILE Result%(NextNumPos) >= 10
                Result%(NextNumPos) = Result%(NextNumPos) - 10
                NextNumPos = NextNumPos + 1
                Result%(NextNumPos) = Result%(NextNumPos) + 1
            LOOP
        NEXT QB
    NEXT SF
    MUL$ = ResultFilter$(Result%(), "MUL", DimSum, PointPos, Sign)
END FUNCTION
 
FUNCTION ResultFilter$ (Result%(), Code$, DimLength, PointPos, Sign)
    SELECT CASE Code$
        CASE "ADD"
            FOR I = 1 TO DimLength - 1
                IF I = PointPos THEN Tiller$ = "." + Tiller$
                Tiller$ = LTRIM$(STR$(Result%(I))) + Tiller$
            NEXT I
            IF Result%(DimLength) <> 0 THEN
                Tiller$ = LTRIM$(STR$(Result%(DimLength))) + Tiller$
            END IF
            IF PointPos <> 0 THEN
                StrLength = LEN(Tiller$)
                CALL DelRightNull(Result%(), Tiller$, StrLength, PointPos)
            END IF
            IF Sign = 1 THEN Tiller$ = "-" + Tiller$
        CASE "SUB"
            FOR I = 1 TO DimLength
                IF I = PointPos THEN Tiller$ = "." + Tiller$
                Tiller$ = LTRIM$(STR$(Result%(I))) + Tiller$
            NEXT I
            IF PointPos <> 0 THEN
                StrLength = LEN(Tiller$)
                CALL DelRightNull(Result%(), Tiller$, StrLength, PointPos)
                CALL DelLeftNull(Result%(), Tiller$, StrLength, DimLength, PointPos)
            ELSE
                CALL DelNull(Result%(), Tiller$, DimLength)
            END IF
            IF Sign = -1 THEN Tiller$ = "-" + Tiller$
        CASE "MUL"
            FOR I = 1 TO DimLength
                Tiller$ = LTRIM$(STR$(Result%(I))) + Tiller$
                IF I = PointPos THEN Tiller$ = "." + Tiller$
            NEXT I
            IF Result%(DimLength) = 0 THEN
                IF PointPos = 0 THEN
                    Tiller$ = RIGHT$(Tiller$, DimLength - 1)
                    IF MID$(Tiller$, 1, 1) = "0" THEN Tiller$ = "0"
                ELSE
                    PointPos = PointPos + 1
                    Tiller$ = RIGHT$(Tiller$, DimLength)
                    StrLength = LEN(Tiller$)
                    TrueDimLength = StrLength - 1
                    CALL DelRightNull(Result%(), Tiller$, StrLength, PointPos)
                    CALL DelLeftNull(Result%(), Tiller$, StrLength, TrueDimLength, PointPos)
                END IF
            END IF
            IF Sign = 1 THEN Tiller$ = "-" + Tiller$
    END SELECT
    IF RIGHT$(Tiller$, 2) = ".0" THEN Tiller$ = LEFT$(Tiller$, LEN(Tiller$) - 2)
    IF Tiller$ = "-0" THEN Tiller$ = "0"
    ResultFilter$ = Tiller$
END FUNCTION
 
FUNCTION SUBqb$ (Minuend$, Subtrahend$)
    MinuSign$ = MID$(Minuend$, 1, 1)
    SubtraSign$ = MID$(Subtrahend$, 1, 1)
    MinuLength = LEN(Minuend$)
    SubtraLength = LEN(Subtrahend$)
    IF MinuSign$ = "-" AND SubtraSign$ <> "-" THEN
        Mediator$ = RIGHT$(Minuend$, MinuLength - 1)
        SUBqb$ = "-" + ADD$(Mediator$, Subtrahend$)
        EXIT FUNCTION
    END IF
    IF MinuSign$ <> "-" AND SubtraSign$ = "-" THEN
        Mediator$ = RIGHT$(Subtrahend$, SubtraLength - 1)
        SUBqb$ = ADD$(Minuend$, Mediator$)
        EXIT FUNCTION
    END IF
    IF MinuSign$ = "-" AND SubtraSign$ = "-" THEN
        SWAP Minuend$, Subtrahend$
        MinuLength = MinuLength - 1
        SubtraLength = SubtraLength - 1
        Minuend$ = RIGHT$(Minuend$, MinuLength)
        Subtrahend$ = RIGHT$(Subtrahend$, SubtraLength)
    END IF
    REDIM Minu%(1 TO MinuLength)
    REDIM Subtra%(1 TO SubtraLength)
    CALL Convert(Minu%(), Minuend$, MinuLength, MinuFlag, MinuPointPos)
    MinuTrueLength = MinuLength - MinuPointPos
    CALL Convert(Subtra%(), Subtrahend$, SubtraLength, SubtraFlag, SubtraPointPos)
    SubtraTrueLength = SubtraLength - SubtraPointPos
    IF SubtraTrueLength > MinuTrueLength THEN
        MainTrueLength = SubtraTrueLength
    ELSE
        MainTrueLength = MinuTrueLength
    END IF
    CompareCode = Compare%(Minuend$, Subtrahend$)
    IF CompareCode = -1 THEN Sign = -1 ELSE Sign = 1
    IF MinuPointPos < SubtraPointPos THEN
        BigPointPos = SubtraPointPos
        TrueBigPointPos = BigPointPos - SubtraFlag
        MinuSub = MinuPointPos - MinuFlag - TrueBigPointPos
    ELSE
        BigPointPos = MinuPointPos
        TrueBigPointPos = BigPointPos - MinuFlag
        SubtraSub = SubtraPointPos - SubtraFlag - TrueBigPointPos
    END IF
    DimSum = MainTrueLength + TrueBigPointPos
    REDIM Result%(1 TO DimSum)
    FOR SF = 1 TO DimSum
        MinuDim = 0
        SubtraDim = 0
        MinuSub = MinuSub + 1
        SubtraSub = SubtraSub + 1
        IF MinuSub > 0 AND MinuSub <= MinuLength - MinuFlag THEN
            MinuDim = Minu%(MinuSub)
        END IF
        IF SubtraSub > 0 AND SubtraSub <= SubtraLength - SubtraFlag THEN
            SubtraDim = Subtra%(SubtraSub)
        END IF
        IF Sign = 1 THEN
            MinuDim = MinuDim + SubFlag
        ELSE
            SubtraDim = SubtraDim + SubFlag
        END IF
        SubSum = Sign * (MinuDim - SubtraDim)
        SubFlag = 0
        IF Sign = 1 THEN
            IF MinuDim >= SubtraDim THEN
                Result%(SF) = SubSum
            ELSE
                IF SubSum < 0 THEN SubFlag = -1
                Result%(SF) = SubSum + 10
            END IF
        ELSE
            IF MinuDim > SubtraDim THEN
                IF SubSum < 0 THEN SubFlag = -1
                Result%(SF) = SubSum + 10
            ELSE
                Result%(SF) = SubSum
            END IF
        END IF
    NEXT SF
    SUBqb$ = ResultFilter$(Result%(), "SUB", DimSum, BigPointPos, Sign)
END FUNCTION
 

@luke @Pete @bplus @George McGinn

Add-on:
Having seen @bplus' results wanted to benchmark my arithmetic library with Fibonacci - the speed is awful, 20x slower, :(

https://www.qb64.org/forum/index.php?topic=2921.msg133317#msg133317

Also, here comes the 10000! benchmark, have to change the INT to LNG (i.e. all % to &) in order to work with 32+K strings:

jack · « **Reply #1 on:** June 19, 2021, 11:45:28 am »

hello Sanmayce
interesting, I bet you could speed-up your code a lot if instead of doing one digit at a time you do 8 or 9 digits at a time
for addition and subtraction you could possibly use _Integer64 for the elements and process 18 digits at a time
a 9 digit product will fit in an _Integer64, so you could use longs for multiplication
also you could transfer your numeric string to an array of longs or _Integer64, that would simplify accessing the elements, then after the operation was finished transfer the array back to string

George McGinn · « **Reply #2 on:** June 19, 2021, 12:32:34 pm »

I see a problem with the division -

When I put this statement in: PRINT DIV$("22", "7", 150) to calculate the value of PI out to 150 decimal places, it repeats a pattern after 7 decimals (see below).

jack · « **Reply #3 on:** June 19, 2021, 12:55:08 pm »

George, there's no error, the output is correct

jack · « **Reply #4 on:** June 19, 2021, 02:06:49 pm »

speaking of Pi

Code: QB64: [Select]

 
digits = 100
beginT# = Timer
a$ = arc_tan$(57, digits)
pi$ = MUL$(a$, "44")
a$ = arc_tan$(239, digits)
a$ = MUL$(a$, "7")
pi$ = ADD$(pi$, a$)
a$ = arc_tan$(682, digits)
a$ = MUL$(a$, "12")
pi$ = SUBqb$(pi$, a$)
a$ = arc_tan$(12943, digits)
a$ = MUL$(a$, "24")
pi$ = ADD$(pi$, a$)
pi$ = MUL$(pi$, "4")
pi$ = Left$(pi$, digits + 2)
Print
Print "Pi = "; pi$
 
Print "Done in"; Timer - beginT#; "seconds."
End
 
DefLng A-Z
Function arc_tan$ (d As Long, digits As Long)
    Dim As Long i
    Dim As String arr1, arr2, arr_help
    i = 1
    arr_help = "1"
 
    arr_help = DIV$(arr_help, LTrim$(Str$(d)), digits + 4)
    arr1 = ADD$(arr1, arr_help)
 
    Do
        arr_help = DIV$(arr_help, LTrim$(Str$(d)), digits + 4)
        arr_help = DIV$(arr_help, LTrim$(Str$(d)), digits + 4)
        i = i + 2
        ' copy arr_help into arr2
        arr2 = arr_help
        arr2 = DIV$(arr2, LTrim$(Str$(i)), digits + 4)
        arr1 = SUBqb$(arr1, arr2)
        arr_help = DIV$(arr_help, LTrim$(Str$(d)), digits + 4)
        arr_help = DIV$(arr_help, LTrim$(Str$(d)), digits + 4)
        i = i + 2
        ' copy arr_help into arr2
        arr2 = arr_help
        arr2 = DIV$(arr2, LTrim$(Str$(i)), digits + 4)
        arr1 = ADD$(arr1, arr2)
        If Compare&(arr2, "0." + String$(digits + 3, "0") + "1") >= 0 Then GoTo Continue
        ' we get here only if arr2 is filled with zero's ("0")
        Exit Do
        Continue:
    Loop
    arc_tan = arr1
End Function
 

George McGinn · « **Reply #5 on:** June 19, 2021, 02:49:29 pm »

@jack - You are right.

I tried this for more precision (77/2 just approximates PI): PRINT DIV$("245850922", "78256779", 150)

That got me much further into the number - about 50 to 80 decimal places before I had repeaters.

Sanmayce · « **Reply #6 on:** June 20, 2021, 03:39:39 am »

Hi jack,
thanks for the suggestions, I am always open to new ideas, but these months I have no time even for my kinda frozen Textual-Madness project. The shared school-method basic arithmetic functions were written in QuickBasic 2.0 as an expression of ... stringomania.

Regarding, digit-to-digit optimization, I rewrote the multiplication in C using lookup tables and ... the Karatsuba scheme - 16 threaded, you know, just for fun purposes and benchmarking.

@david_uwi

The attached MokujIN package has the EXE/ELF and the C source which computes (as command prompt parameters) 524288^^524288 = (2^^19)^^(2^^19) = 2^^(19*524288) = 2^^(9961472) ...

This is the laddy called Anatoly Karatsuba, the nightmare for Akad. Kolmogorov:

This PDF is very instrumental, for all wanting to get the down-the-years picture:
https://www.math.ntnu.no/seminarer/perler/2019-09-06.pdf

My adash (an orientalism, meaning 'namesake') and you jack, might find this interesting (the unseen slowness of Intel CPUs, shown by my humble persona, was one of the reasons to get me banned from IDZ - Intel Developer Zone forum, as if it was my fault, an ugly behavior indeed):
https://www.overclock.net/threads/cpu-benchmark-spigot-pi.1752820/#post-28567752

Thinking from another perspective, I got awarded with 'BAN', for several years of sharing my C code.

Anyway, wrote another short CONSOLE tool dumping Fibonacci numbers in a file, it finds 1000th number in 239 seconds on i5-7200U:

And loading this 275KB file (attached below) into Masakari_Vanilla_NEC (with 300x80 matrix):

jack · « **Reply #7 on:** June 20, 2021, 06:09:42 am »

Hi Sanmayce
very interesting reads and code, thank you

euklides · « **Reply #8 on:** June 23, 2021, 05:24:14 am »

This program would be very useful for calculating spatial trajectories (+ a bit of trigonometry).
Interesting.
Also for the search of prime numbers ...

News:

Author Topic: Simulating Addition/Subtraction/Multiplication/Division via strings (Read 4593 times)

Sanmayce

Simulating Addition/Subtraction/Multiplication/Division via strings

jack

Re: Simulating Addition/Subtraction/Multiplication/Division via strings

George McGinn

Re: Simulating Addition/Subtraction/Multiplication/Division via strings

jack

Re: Simulating Addition/Subtraction/Multiplication/Division via strings

jack

Re: Simulating Addition/Subtraction/Multiplication/Division via strings

George McGinn

Re: Simulating Addition/Subtraction/Multiplication/Division via strings

Sanmayce

Re: Simulating Addition/Subtraction/Multiplication/Division via strings

jack

Re: Simulating Addition/Subtraction/Multiplication/Division via strings

euklides

Re: Simulating Addition/Subtraction/Multiplication/Division via strings