From e73ce2f8bca28fa877e9cbac20dad6520a7446ff Mon Sep 17 00:00:00 2001
From: Tomasz Sowa <t.sowa@ttmath.org>
Date: Sun, 1 Nov 2009 13:26:19 +0000
Subject: [PATCH] added: UInt::Sqrt() - a new algorithm for calculating the
 square root

git-svn-id: svn://ttmath.org/publicrep/ttmath/trunk@228 e52654a7-88a9-db11-a3e9-0013d4bc506e
---
 CHANGELOG           |  1 +
 ttmath/ttmathbig.h  |  1 +
 ttmath/ttmathint.h  |  1 +
 ttmath/ttmathuint.h | 44 ++++++++++++++++++++++++++++++++++++++++++++
 4 files changed, 47 insertions(+)

diff --git a/CHANGELOG b/CHANGELOG
index 5931319..9d11e93 100644
--- a/CHANGELOG
+++ b/CHANGELOG
@@ -44,6 +44,7 @@ Version 0.9.0 prerelease (2009.11.01):
                uint FromString(const wchar_t * source, const Conv & conv, const wchar_t **, bool *)
                uint FromString(const std::string & string, const Conv & conv, const wchar_t **, bool *)
                uint FromString(const std::wstring & string, const Conv & conv, const wchar_t **, bool *)
+    * added:   UInt::Sqrt() - a new algorithm for calculating the square root
     * changed: Factorial() is using the Gamma() function now
     * changed: Big::Div(ss2)
                Big::Mod(ss2)
diff --git a/ttmath/ttmathbig.h b/ttmath/ttmathbig.h
index 1cddf0e..f7a4680 100644
--- a/ttmath/ttmathbig.h
+++ b/ttmath/ttmathbig.h
@@ -1509,6 +1509,7 @@ public:
 	}
 
 
+
 private:
 
 #ifdef TTMATH_CONSTANTSGENERATOR
diff --git a/ttmath/ttmathint.h b/ttmath/ttmathint.h
index 260ad39..cc89064 100644
--- a/ttmath/ttmathint.h
+++ b/ttmath/ttmathint.h
@@ -534,6 +534,7 @@ public:
 	}
 
 
+
 	/*!
 	*
 	*	convertion methods
diff --git a/ttmath/ttmathuint.h b/ttmath/ttmathuint.h
index 0bc9a6a..7c6e5a8 100644
--- a/ttmath/ttmathuint.h
+++ b/ttmath/ttmathuint.h
@@ -2252,6 +2252,50 @@ public:
 	}
 
 
+	/*!
+		square root
+		e.g. Sqrt(9) = 3
+		('digit-by-digit' algorithm)
+	*/
+	void Sqrt()
+	{
+	UInt<value_size> bit, temp;
+
+		if( IsZero() )
+			return;
+
+		UInt<value_size> value(*this);
+
+		SetZero();
+		bit.SetZero();
+		bit.table[value_size-1] = (TTMATH_UINT_HIGHEST_BIT >> 1);
+		
+		while( bit > value )
+			bit.Rcr(2);
+
+		while( !bit.IsZero() )
+		{
+			temp = *this;
+			temp.Add(bit);
+
+			if( value >= temp )
+			{
+				value.Sub(temp);
+				Rcr(1);
+				Add(bit);
+			}
+			else
+			{
+				Rcr(1);
+			}
+
+			bit.Rcr(2);
+		}
+
+		TTMATH_LOG("UInt::Sqrt")
+	}
+
+
 
 	/*!
 		this method sets n first bits to value zero