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Convert vbscript function to C#

Posted on 2012-03-30
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Last Modified: 2012-04-04
I need to convert the following vb script function to C# to be used in a new application.
Function EX(ByRef x, p, m)
    y = 1
    Do While p > 0
        Do While (p / 2) = Int((p / 2))
            x = (x * x) - (Int((x * x) / m) * m)
            p = p / 2
        Loop
        y = (x * y) - (Int((x * y) / m) * m)
        p = p - 1
    Loop
    EX = y
End Function

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This is my attempt, but it does not work correctly. The original returns y as a number less than 1000 and my conversion returns numbers in the millions and runs many more iterations of the inner loop.

       public int Ex(ref int x, int p, int m)
        {
            y = 1;
            do
            {
                do
                {
                    x = (x * x) - (((x * x) / m) * m);
                    p = p / 2;
                }
                while ((p % 2) == 0);
                y = (x * y) - (((x * y) / m) * m);
                p = p - 1;
            }
            while (p > 0);
            return y;
        }

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I have attached another version of the vbscript function with logging statements and the logs it generated so you can see the data involved since they used no datatypes when it was written.

Function EX(ByRef x, p, m)
	logmessage "gis.asp: EX", "	Variables passed in: x = " & x & " p = " & p & " m = " & m
    y = 1
    i =1
    o =1
    Do While p > 0
        Do While (p / 2) = Int((p / 2))
            x = (x * x) - (Int((x * x) / m) * m)
            logmessage "gis.asp: EX", "		(x * x)" & (x * x) & " - (Int((x * x) / m)" & Int((x * x) / m) & " * m)" & (Int((x * x) / m) * m) & " = " & (x * x) - (Int((x * x) / m) * m)
            p = p / 2
            logmessage "gis.asp: EX", "		inner iteration"& i &": p/2 = " & p/2 & " p = " & p & " y = " & y & " x = " & x
            i = i + 1
        Loop
			logmessage "gis.asp: EX", "	post inner do: p = " & p & " y = " & y & " x = " & x
			i=1
        y = (x * y) - (Int((x * y) / m) * m)
        p = p - 1
            logmessage "gis.asp: EX", "	outer iteration"& o &": p = " & p & " y = " & y & " x = " & x
            o = o + 1
    Loop
    o=1
        logmessage "gis.asp: EX", "post outer do: p = " & p & " y = " & y & " x = " & x
    EX = y
End Function


3/30/2012 9:26:46 AM	gis.asp: EX		Variables passed in: x = 15344606 p = 18346651 m = 22833299
3/30/2012 9:26:46 AM	gis.asp: EX		post inner do: p = 18346651 y = 1 x = 15344606
3/30/2012 9:26:46 AM	gis.asp: EX		outer iteration1: p = 18346650 y = 15344606 x = 15344606
3/30/2012 9:26:46 AM	gis.asp: EX			(x * x)506571035879689 - (Int((x * x) / m)22185626 * m)506571031960174 = 3919515
3/30/2012 9:26:46 AM	gis.asp: EX			inner iteration1: p/2 = 4586662.5 p = 9173325 y = 15344606 x = 22507133
3/30/2012 9:26:46 AM	gis.asp: EX		post inner do: p = 9173325 y = 15344606 x = 22507133
3/30/2012 9:26:46 AM	gis.asp: EX		outer iteration2: p = 9173324 y = 10547111 x = 22507133
3/30/2012 9:26:46 AM	gis.asp: EX			(x * x)15362597835225 - (Int((x * x) / m)672815 * m)15362586066685 = 11768540
3/30/2012 9:26:46 AM	gis.asp: EX			inner iteration1: p/2 = 2293331 p = 4586662 y = 10547111 x = 3919515
3/30/2012 9:26:46 AM	gis.asp: EX			(x * x)138498533731600 - (Int((x * x) / m)6065638 * m)138498526079762 = 7651838
3/30/2012 9:26:46 AM	gis.asp: EX			inner iteration2: p/2 = 1146665.5 p = 2293331 y = 10547111 x = 11768540
3/30/2012 9:26:46 AM	gis.asp: EX		post inner do: p = 2293331 y = 10547111 x = 11768540
3/30/2012 9:26:46 AM	gis.asp: EX		outer iteration3: p = 2293330 y = 994040 x = 11768540
3/30/2012 9:26:46 AM	gis.asp: EX			(x * x)58550624778244 - (Int((x * x) / m)2564264 * m)58550606626936 = 18151308
3/30/2012 9:26:46 AM	gis.asp: EX			inner iteration1: p/2 = 573332.5 p = 1146665 y = 994040 x = 7651838
3/30/2012 9:26:46 AM	gis.asp: EX		post inner do: p = 1146665 y = 994040 x = 7651838
3/30/2012 9:26:46 AM	gis.asp: EX		outer iteration4: p = 1146664 y = 4482640 x = 7651838
3/30/2012 9:26:46 AM	gis.asp: EX			(x * x)329469982110864 - (Int((x * x) / m)14429363 * m)329469959758537 = 22352327
3/30/2012 9:26:46 AM	gis.asp: EX			inner iteration1: p/2 = 286666 p = 573332 y = 4482640 x = 18151308
3/30/2012 9:26:46 AM	gis.asp: EX			(x * x)499626522314929 - (Int((x * x) / m)21881486 * m)499626512402314 = 9912615
3/30/2012 9:26:46 AM	gis.asp: EX			inner iteration2: p/2 = 143333 p = 286666 y = 4482640 x = 22352327
3/30/2012 9:26:46 AM	gis.asp: EX			(x * x)98259936138225 - (Int((x * x) / m)4303361 * m)98259928417939 = 7720286
3/30/2012 9:26:46 AM	gis.asp: EX			inner iteration3: p/2 = 71666.5 p = 143333 y = 4482640 x = 9912615
3/30/2012 9:26:46 AM	gis.asp: EX		post inner do: p = 143333 y = 4482640 x = 9912615
3/30/2012 9:26:46 AM	gis.asp: EX		outer iteration5: p = 143332 y = 11484547 x = 9912615
3/30/2012 9:26:46 AM	gis.asp: EX			(x * x)59602815921796 - (Int((x * x) / m)2610346 * m)59602810711454 = 5210342
3/30/2012 9:26:46 AM	gis.asp: EX			inner iteration1: p/2 = 35833 p = 71666 y = 11484547 x = 7720286
3/30/2012 9:26:46 AM	gis.asp: EX			(x * x)27147663756964 - (Int((x * x) / m)1188950 * m)27147650846050 = 12910914
3/30/2012 9:26:46 AM	gis.asp: EX			inner iteration2: p/2 = 17916.5 p = 35833 y = 11484547 x = 5210342
3/30/2012 9:26:46 AM	gis.asp: EX		post inner do: p = 35833 y = 11484547 x = 5210342
3/30/2012 9:26:46 AM	gis.asp: EX		outer iteration6: p = 35832 y = 12894538 x = 5210342
3/30/2012 9:26:46 AM	gis.asp: EX			(x * x)166691700315396 - (Int((x * x) / m)7300377 * m)166691690853723 = 9461673
3/30/2012 9:26:46 AM	gis.asp: EX			inner iteration1: p/2 = 8958 p = 17916 y = 12894538 x = 12910914
3/30/2012 9:26:46 AM	gis.asp: EX			(x * x)89523255958929 - (Int((x * x) / m)3920732 * m)89523246054868 = 9904061
3/30/2012 9:26:46 AM	gis.asp: EX			inner iteration2: p/2 = 4479 p = 8958 y = 12894538 x = 9461673
3/30/2012 9:26:46 AM	gis.asp: EX			(x * x)98090424291721 - (Int((x * x) / m)4295937 * m)98090414006163 = 10285558
3/30/2012 9:26:46 AM	gis.asp: EX			inner iteration3: p/2 = 2239.5 p = 4479 y = 12894538 x = 9904061
3/30/2012 9:26:46 AM	gis.asp: EX		post inner do: p = 4479 y = 12894538 x = 9904061
3/30/2012 9:26:46 AM	gis.asp: EX		outer iteration7: p = 4478 y = 5614290 x = 9904061
3/30/2012 9:26:46 AM	gis.asp: EX			(x * x)105792703371364 - (Int((x * x) / m)4633264 * m)105792702257936 = 1113428
3/30/2012 9:26:46 AM	gis.asp: EX			inner iteration1: p/2 = 1119.5 p = 2239 y = 5614290 x = 10285558
3/30/2012 9:26:46 AM	gis.asp: EX		post inner do: p = 2239 y = 5614290 x = 10285558
3/30/2012 9:26:46 AM	gis.asp: EX		outer iteration8: p = 2238 y = 7253850 x = 10285558
3/30/2012 9:26:46 AM	gis.asp: EX			(x * x)1239721911184 - (Int((x * x) / m)54294 * m)1239711135906 = 10775278
3/30/2012 9:26:46 AM	gis.asp: EX			inner iteration1: p/2 = 559.5 p = 1119 y = 7253850 x = 1113428
3/30/2012 9:26:46 AM	gis.asp: EX		post inner do: p = 1119 y = 7253850 x = 1113428
3/30/2012 9:26:47 AM	gis.asp: EX		outer iteration9: p = 1118 y = 22342221 x = 1113428
3/30/2012 9:26:47 AM	gis.asp: EX			(x * x)116106615977284 - (Int((x * x) / m)5084968 * m)116106594749432 = 21227852
3/30/2012 9:26:47 AM	gis.asp: EX			inner iteration1: p/2 = 279.5 p = 559 y = 22342221 x = 10775278
3/30/2012 9:26:47 AM	gis.asp: EX		post inner do: p = 559 y = 22342221 x = 10775278
3/30/2012 9:26:47 AM	gis.asp: EX		outer iteration10: p = 558 y = 907071 x = 10775278
3/30/2012 9:26:47 AM	gis.asp: EX			(x * x)450621700533904 - (Int((x * x) / m)19735286 * m)450621686088514 = 14445390
3/30/2012 9:26:47 AM	gis.asp: EX			inner iteration1: p/2 = 139.5 p = 279 y = 907071 x = 21227852
3/30/2012 9:26:47 AM	gis.asp: EX		post inner do: p = 279 y = 907071 x = 21227852
3/30/2012 9:26:47 AM	gis.asp: EX		outer iteration11: p = 278 y = 7727885 x = 21227852
3/30/2012 9:26:47 AM	gis.asp: EX			(x * x)208669292252100 - (Int((x * x) / m)9138814 * m)208669272567386 = 19684714
3/30/2012 9:26:47 AM	gis.asp: EX			inner iteration1: p/2 = 69.5 p = 139 y = 7727885 x = 14445390
3/30/2012 9:26:47 AM	gis.asp: EX		post inner do: p = 139 y = 7727885 x = 14445390
3/30/2012 9:26:47 AM	gis.asp: EX		outer iteration12: p = 138 y = 17056263 x = 14445390
3/30/2012 9:26:47 AM	gis.asp: EX			(x * x)387487965261796 - (Int((x * x) / m)16970301 * m)387487956852999 = 8408797
3/30/2012 9:26:47 AM	gis.asp: EX			inner iteration1: p/2 = 34.5 p = 69 y = 17056263 x = 19684714
3/30/2012 9:26:47 AM	gis.asp: EX		post inner do: p = 69 y = 17056263 x = 19684714
3/30/2012 9:26:47 AM	gis.asp: EX		outer iteration13: p = 68 y = 3411381 x = 19684714
3/30/2012 9:26:47 AM	gis.asp: EX			(x * x)70707866987209 - (Int((x * x) / m)3096699 * m)70707854180001 = 12807208
3/30/2012 9:26:47 AM	gis.asp: EX			inner iteration1: p/2 = 17 p = 34 y = 3411381 x = 8408797
3/30/2012 9:26:47 AM	gis.asp: EX			(x * x)164024576755264 - (Int((x * x) / m)7183568 * m)164024556030832 = 20724432
3/30/2012 9:26:47 AM	gis.asp: EX			inner iteration2: p/2 = 8.5 p = 17 y = 3411381 x = 12807208
3/30/2012 9:26:47 AM	gis.asp: EX		post inner do: p = 17 y = 3411381 x = 12807208
3/30/2012 9:26:47 AM	gis.asp: EX		outer iteration14: p = 16 y = 4229193 x = 12807208
3/30/2012 9:26:47 AM	gis.asp: EX			(x * x)429502081722624 - (Int((x * x) / m)18810338 * m)429502071845062 = 9877562
3/30/2012 9:26:47 AM	gis.asp: EX			inner iteration1: p/2 = 4 p = 8 y = 4229193 x = 20724432
3/30/2012 9:26:47 AM	gis.asp: EX			(x * x)97566231063844 - (Int((x * x) / m)4272980 * m)97566229961020 = 1102824
3/30/2012 9:26:47 AM	gis.asp: EX			inner iteration2: p/2 = 2 p = 4 y = 4229193 x = 9877562
3/30/2012 9:26:47 AM	gis.asp: EX			(x * x)1216220774976 - (Int((x * x) / m)53265 * m)1216215671235 = 5103741
3/30/2012 9:26:47 AM	gis.asp: EX			inner iteration3: p/2 = 1 p = 2 y = 4229193 x = 1102824
3/30/2012 9:26:47 AM	gis.asp: EX			(x * x)26048172195081 - (Int((x * x) / m)1140797 * m)26048158999303 = 13195778
3/30/2012 9:26:47 AM	gis.asp: EX			inner iteration4: p/2 = 0.5 p = 1 y = 4229193 x = 5103741
3/30/2012 9:26:47 AM	gis.asp: EX		post inner do: p = 1 y = 4229193 x = 5103741
3/30/2012 9:26:47 AM	gis.asp: EX		outer iteration15: p = 0 y = 230 x = 5103741
3/30/2012 9:26:47 AM	gis.asp: EX	post outer do: p = 0 y = 230 x = 5103741

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Question by:dgerler
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4 Comments
 
LVL 28

Assisted Solution

by:sammySeltzer
sammySeltzer earned 100 total points
ID: 37787928
public object EX(ref System.Object x, System.Object p, System.Object m)
{
	y = 1;
	while (p > 0) {
		while ((p / 2) == Conversion.Int((p / 2))) {
			x = (x * x) - (Conversion.Int((x * x) / m) * m);
			p = p / 2;
		}
		y = (x * y) - (Conversion.Int((x * y) / m) * m);
		p = p - 1;
	}
	return y;
}

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http://converter.telerik.com/
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Author Comment

by:dgerler
ID: 37788075
That doesn't compile. Math can't be performed on the objects.

I have modified it to:

        public int Ex(ref int x, int p, int m)
        {
            int y = 1;
            while (p > 0)
            {
                while ((p / 2) == Convert.ToInt32(p/2))
                {
                    x = (x * x) - (Convert.ToInt32((x * x) / m) * m);
                    p = p / 2;
                }
                y = (x * y) - (Convert.ToInt32((x * y) / m) * m);
                p = p - 1;
            }
            return y;
        }

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It still doesn't work correctly.
0
 

Accepted Solution

by:
dgerler earned 0 total points
ID: 37788896
It's fixed.

here's the functioning code..

x*x was overflowing the the int32 datatype and causing the number to go negative.

        public int Ex(ref Int64 x, Int64 p, Int64 m)
        {
            Int64 y = 1;
            while (p > 0)
            {
                while ((p % 2) == 0)
                {
                    x = (x * x) - (Convert.ToInt64((x * x) / m) * m);
                    p = p / 2;
                }
                y = (x * y) - (Convert.ToInt64((x * y) / m) * m);
                p = p - 1;
            }
            return (int)y;
        }

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0
 

Author Closing Comment

by:dgerler
ID: 37805191
While SammySelzer provided some code it was not complete and require much more work to fix it. The main thing I got from it was changing the do..while to a while
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