// ==++==
//
//   Copyright (c) Microsoft Corporation.  All rights reserved.
//
// ==--==
/*============================================================
**
** Class:  Math
**
**
** Purpose: Some floating-point math operations
**
** Date:  July 8, 1998
**
===========================================================*/
namespace System {

    using System;
    using System.Runtime.CompilerServices;
    using System.Runtime.InteropServices;

    //| <include path='docs/doc[@for="Math"]/*' />
    [CCtorIsRunDuringStartup]
    public sealed class Math {

        // Prevent from begin created
        private Math() {}

        //| <include path='docs/doc[@for="Math.PI"]/*' />
        public const double PI = 3.14159265358979323846;
        //| <include path='docs/doc[@for="Math.E"]/*' />
        public const double E  = 2.7182818284590452354;


        //| <include path='docs/doc[@for="Math.Acos"]/*' />
        [MethodImpl(MethodImplOptions.InternalCall)]
        [GCAnnotation(GCOption.NOGC)]
        [StackBound(128)]
        [AccessedByRuntime("output to header : defined in Math.cpp")]
        public static extern double Acos(double d);

        //| <include path='docs/doc[@for="Math.Asin"]/*' />
        [MethodImpl(MethodImplOptions.InternalCall)]
        [GCAnnotation(GCOption.NOGC)]
        [StackBound(128)]
        [AccessedByRuntime("output to header : defined in Math.cpp")]
        public static extern double Asin(double d);

        //| <include path='docs/doc[@for="Math.Atan"]/*' />
        [MethodImpl(MethodImplOptions.InternalCall)]
        [GCAnnotation(GCOption.NOGC)]
        [StackBound(128)]
        [AccessedByRuntime("output to header : defined in Math.cpp")]
        public static extern double Atan(double d);

        //| <include path='docs/doc[@for="Math.Atan2"]/*' />
        [MethodImpl(MethodImplOptions.InternalCall)]
        [GCAnnotation(GCOption.NOGC)]
        [StackBound(128)]
        [AccessedByRuntime("output to header : defined in Math.cpp")]
        public static extern double Atan2(double y, double x);

        //| <include path='docs/doc[@for="Math.Cos"]/*' />
        [MethodImpl(MethodImplOptions.InternalCall)]
        [StackBound(128)]
        [AccessedByRuntime("output to header : defined in Math.cpp")]
        public static extern double Cos(double d);

        //| <include path='docs/doc[@for="Math.Sin"]/*' />
        [MethodImpl(MethodImplOptions.InternalCall)]
        [StackBound(128)]
        [AccessedByRuntime("output to header : defined in Math.cpp")]
        public static extern double Sin(double a);

        //| <include path='docs/doc[@for="Math.Tan"]/*' />
        [MethodImpl(MethodImplOptions.InternalCall)]
        [GCAnnotation(GCOption.NOGC)]
        [StackBound(128)]
        [AccessedByRuntime("output to header : defined in Math.cpp")]
        public static extern double Tan(double a);

        //| <include path='docs/doc[@for="Math.Cosh"]/*' />
        [MethodImpl(MethodImplOptions.InternalCall)]
        [GCAnnotation(GCOption.NOGC)]
        [StackBound(512)]
        [AccessedByRuntime("output to header : defined in Math.cpp")]
        public static extern double Cosh(double value);

        //| <include path='docs/doc[@for="Math.Sinh"]/*' />
        [MethodImpl(MethodImplOptions.InternalCall)]
        [GCAnnotation(GCOption.NOGC)]
        [StackBound(512)]
        [AccessedByRuntime("output to header : defined in Math.cpp")]
        public static extern double Sinh(double value);

        //| <include path='docs/doc[@for="Math.Tanh"]/*' />
        [MethodImpl(MethodImplOptions.InternalCall)]
        [GCAnnotation(GCOption.NOGC)]
        [StackBound(256)]
        [AccessedByRuntime("output to header : defined in Math.cpp")]
        public static extern double Tanh(double value);

        //| <include path='docs/doc[@for="Math.Round"]/*' />
        [MethodImpl(MethodImplOptions.InternalCall)]
        [GCAnnotation(GCOption.NOGC)]
        [StackBound(128)]
        [AccessedByRuntime("output to header : defined in Math.cpp")]
        public static extern double Round(double a);

        private static double NegativeZero
        = BitConverter.UInt64BitsToDouble(0x8000000000000000);

        private const int maxRoundingDigits = 15;
        //| <include path='docs/doc[@for="Math.Round2"]/*' />
        public static double Round(double value, int digits)
        {
            if ((digits < 0) || (digits > maxRoundingDigits)) {
                throw new ArgumentOutOfRangeException("ArgumentOutOfRange_RoundingDigits");
            }
            return InternalRound(value,digits);
        }

        private static double InternalRound(double d, int digits) {
            // rusa: see also Lightning\Src\ClassLibNative\Float\COMFloat.cpp::RoundDigits
            // Managed code ensures that (digits >= 0 && digits <= 15)
            if (Abs(d) < 1E16) {
                d *= dblPower10[digits];
                // There is a short x86 code sequence for the Round operation
                // __asm {
                //     fld d;
                //     frndint
                //     fstp d;
                // }
                d = Round(d);
                d /= dblPower10[digits];
            }
            return d;
        }

        private static readonly double[] dblPower10 = new double[16] {
            1E0, 1E1, 1E2, 1E3, 1E4, 1E5, 1E6, 1E7, 1E8,
            1E9, 1E10, 1E11, 1E12, 1E13, 1E14, 1E15
        };

        //| <include path='docs/doc[@for="Math.Round1"]/*' />
        public static Decimal Round(Decimal d)
        {
            return Decimal.Round(d,0);
        }

        //| <include path='docs/doc[@for="Math.Round3"]/*' />
        public static Decimal Round(Decimal d, int decimals)
        {
            return Decimal.Round(d,decimals);
        }

        //| <include path='docs/doc[@for="Math.Ceiling"]/*' />
        [MethodImpl(MethodImplOptions.InternalCall)]
        [GCAnnotation(GCOption.NOGC)]
        [StackBound(128)]
        [AccessedByRuntime("output to header : defined in Math.cpp")]
        public static extern double Ceiling(double a);

        //| <include path='docs/doc[@for="Math.Floor"]/*' />
        [MethodImpl(MethodImplOptions.InternalCall)]
        [GCAnnotation(GCOption.NOGC)]
        [StackBound(128)]
        [AccessedByRuntime("output to header : defined in Math.cpp")]
        public static extern double Floor(double d);

        //| <include path='docs/doc[@for="Math.Sqrt"]/*' />
        [MethodImpl(MethodImplOptions.InternalCall)]
        [StackBound(128)]
        [AccessedByRuntime("output to header : defined in Math.cpp")]
        public static extern double Sqrt(double d);

        //| <include path='docs/doc[@for="Math.Log"]/*' />
        [MethodImpl(MethodImplOptions.InternalCall)]
        [GCAnnotation(GCOption.NOGC)]
        [StackBound(128)]
        [AccessedByRuntime("output to header : defined in Math.cpp")]
        public static extern double Log(double d);

        //| <include path='docs/doc[@for="Math.Log10"]/*' />
        [MethodImpl(MethodImplOptions.InternalCall)]
        [GCAnnotation(GCOption.NOGC)]
        [StackBound(128)]
        [AccessedByRuntime("output to header : defined in Math.cpp")]
        public static extern double Log10(double d);

        //| <include path='docs/doc[@for="Math.Exp"]/*' />
        [MethodImpl(MethodImplOptions.InternalCall)]
        [GCAnnotation(GCOption.NOGC)]
        [StackBound(128)]
        [AccessedByRuntime("output to header : defined in Math.cpp")]
        public static extern double Exp(double d);

        //| <include path='docs/doc[@for="Math.Pow"]/*' />
        [MethodImpl(MethodImplOptions.InternalCall)]
        [GCAnnotation(GCOption.NOGC)]
        [StackBound(128)]
        [AccessedByRuntime("output to header : defined in Math.cpp")]
        public static extern double Pow(double x, double y);

        //| <include path='docs/doc[@for="Math.Mod"]/*' />
        [MethodImpl(MethodImplOptions.InternalCall)]
        [GCAnnotation(GCOption.NOGC)]
        [StackBound(128)]
        [AccessedByRuntime("output to header : defined in Math.cpp")]
        public static extern double Mod(double x, double y);

        //| <include path='docs/doc[@for="Math.IEEERemainder"]/*' />
        [GCAnnotation(GCOption.NOGC)]
        public static double IEEERemainder(double x, double y)
        {
            double val = (x - (y * (Math.Round(x / y))));
            if (val == 0) {
                if (x < 0) {
                    return NegativeZero; // this can be turned into a static if people like
                }
            }
            return val;
        }

        /*================================Abs=========================================
        **Returns the absolute value of its argument.
        ============================================================================*/
        //| <include path='docs/doc[@for="Math.Abs"]/*' />
        [CLSCompliant(false)]
        public static sbyte Abs(sbyte value) {
            if (value >= 0) {
                return value;
            }
            else {
                return AbsHelper(value);
            }
        }

        private static sbyte AbsHelper(sbyte value)
        {
            if (value < 0) {
                if (value == SByte.MinValue) {
                    throw new OverflowException("Overflow_NegateTwosCompNum");
                }
                return ((sbyte)(-value));
            }
            return value;
        }

        //| <include path='docs/doc[@for="Math.Abs1"]/*' />
        public static short Abs(short value) {
            if (value >= 0) {
                return value;
            }
            else {
                return AbsHelper(value);
            }
        }

        private static short AbsHelper(short value) {
            if (value < 0) {
                if (value == Int16.MinValue) {
                    throw new OverflowException("Overflow_NegateTwosCompNum");
                }
                return (short) -value;
            }
            return value;
        }

        //| <include path='docs/doc[@for="Math.Abs2"]/*' />
        public static int Abs(int value) {
            if (value >= 0) {
                return value;
            }
            else {
                return AbsHelper(value);
            }
        }

        private static int AbsHelper(int value) {
            if (value < 0) {
                if (value == Int32.MinValue) {
                    throw new OverflowException("Overflow_NegateTwosCompNum");
                }
                return -value;
            }
            return value;
        }

        //| <include path='docs/doc[@for="Math.Abs3"]/*' />
        public static long Abs(long value) {
            if (value >= 0) {
                return value;
            }
            else {
                return AbsHelper(value);
            }
        }

        private static long AbsHelper(long value) {
            if (value < 0) {
                if (value == Int64.MinValue) {
                    throw new OverflowException("Overflow_NegateTwosCompNum");
                }
                return -value;
            }
            return value;
        }

        //| <include path='docs/doc[@for="Math.Abs4"]/*' />
        [Intrinsic]
        extern public static float Abs(float value);
        // This is special code to handle NaN (We need to make sure NaN's aren't
        // negated).  In Cool, the else clause here should always be taken if
        // value is NaN, since the normal case is taken if and only if value < 0.
        // To illustrate this completely, a compiler has translated this into:
        // "load value; load 0; bge; ret -value ; ret value".
        // The bge command branches for comparisons with the unordered NaN.  So
        // it runs the else case, which returns +value instead of negating it.
        //  return (value < 0) ? -value : value;

        //| <include path='docs/doc[@for="Math.Abs5"]/*' />
        [MethodImpl(MethodImplOptions.InternalCall)]
        [StackBound(128)]
        [AccessedByRuntime("output to header : defined in Math.cpp")]
        extern public static double Abs(double value);
        // This is special code to handle NaN (We need to make sure NaN's aren't
        // negated).  In Cool, the else clause here should always be taken if
        // value is NaN, since the normal case is taken if and only if value < 0.
        // To illustrate this completely, a compiler has translated this into:
        // "load value; load 0; bge; ret -value ; ret value".
        // The bge command branches for comparisons with the unordered NaN.  So
        // it runs the else case, which returns +value instead of negating it.
        // return (value < 0) ? -value : value;

        //| <include path='docs/doc[@for="Math.Abs6"]/*' />
        public static Decimal Abs(Decimal value)
        {
            return Decimal.Abs(value);
        }

        /*================================MAX=========================================
        **Returns the larger of val1 and val2
        ============================================================================*/
        //| <include path='docs/doc[@for="Math.Max"]/*' />
        [CLSCompliant(false)]
        public static sbyte Max(sbyte val1, sbyte val2) {
            return (val1 >= val2) ? val1 : val2;
        }

        //| <include path='docs/doc[@for="Math.Max1"]/*' />
        public static byte Max(byte val1, byte val2) {
            return (val1 >= val2) ? val1 : val2;
        }

        //| <include path='docs/doc[@for="Math.Max2"]/*' />
        public static short Max(short val1, short val2) {
            return (val1 >= val2) ? val1 : val2;
        }

        //| <include path='docs/doc[@for="Math.Max3"]/*' />
        [CLSCompliant(false)]
        public static ushort Max(ushort val1, ushort val2) {
            return (val1 >= val2) ? val1 : val2;
        }

        //| <include path='docs/doc[@for="Math.Max4"]/*' />
        public static int Max(int val1, int val2) {
            return (val1 >= val2) ? val1 : val2;
        }

        //| <include path='docs/doc[@for="Math.Max5"]/*' />
        [CLSCompliant(false)]
        public static uint Max(uint val1, uint val2) {
            return (val1 >= val2) ? val1 : val2;
        }

        //| <include path='docs/doc[@for="Math.Max6"]/*' />
        public static long Max(long val1, long val2) {
            return (val1 >= val2) ? val1 : val2;
        }

        //| <include path='docs/doc[@for="Math.Max7"]/*' />
        [CLSCompliant(false)]
        public static ulong Max(ulong val1, ulong val2) {
            return (val1 >= val2) ? val1 : val2;
        }

        //| <include path='docs/doc[@for="Math.Max8"]/*' />
        public static float Max(float val1, float val2) {
            if (val1 > val2) {
                return val1;
            }
            if (Single.IsNaN(val1)) {
                return val1;
            }
            return val2;
        }

        //| <include path='docs/doc[@for="Math.Max9"]/*' />
        public static double Max(double val1, double val2) {
            if (val1 > val2) {
                return val1;
            }
            if (Double.IsNaN(val1)) {
                return val1;
            }
            return val2;
        }

        //| <include path='docs/doc[@for="Math.Max10"]/*' />
        public static Decimal Max(Decimal val1, Decimal val2) {
            return Decimal.Max(val1, val2);
        }

        /*================================MIN=========================================
        **Returns the smaller of val1 and val2.
        ============================================================================*/
        //| <include path='docs/doc[@for="Math.Min"]/*' />
        [CLSCompliant(false)]
        public static sbyte Min(sbyte val1, sbyte val2) {
            return (val1 <= val2) ? val1 : val2;
        }

        //| <include path='docs/doc[@for="Math.Min1"]/*' />
        public static byte Min(byte val1, byte val2) {
            return (val1 <= val2) ? val1 : val2;
        }

        //| <include path='docs/doc[@for="Math.Min2"]/*' />
        public static short Min(short val1, short val2) {
            return (val1 <= val2) ? val1 : val2;
        }

        //| <include path='docs/doc[@for="Math.Min3"]/*' />
        [CLSCompliant(false)]
        public static ushort Min(ushort val1, ushort val2) {
            return (val1 <= val2) ? val1 : val2;
        }

        //| <include path='docs/doc[@for="Math.Min4"]/*' />
        public static int Min(int val1, int val2) {
            return (val1 <= val2) ? val1 : val2;
        }

        //| <include path='docs/doc[@for="Math.Min5"]/*' />
        [CLSCompliant(false)]
        public static uint Min(uint val1, uint val2) {
            return (val1 <= val2) ? val1 : val2;
        }

        //| <include path='docs/doc[@for="Math.Min6"]/*' />
        public static long Min(long val1, long val2) {
            return (val1 <= val2) ? val1 : val2;
        }

        //| <include path='docs/doc[@for="Math.Min7"]/*' />
        [CLSCompliant(false)]
        public static ulong Min(ulong val1, ulong val2) {
            return (val1 <= val2) ? val1 : val2;
        }

        //| <include path='docs/doc[@for="Math.Min8"]/*' />
        public static float Min(float val1, float val2) {
            if (val1 < val2) {
                return val1;
            }
            if (Single.IsNaN(val1)) {
                return val1;
            }
            return val2;
        }

        //| <include path='docs/doc[@for="Math.Min9"]/*' />
        public static double Min(double val1, double val2) {
            if (val1 < val2) {
                return val1;
            }
            if (Double.IsNaN(val1)) {
                return val1;
            }
            return val2;
        }

        //| <include path='docs/doc[@for="Math.Min10"]/*' />
        public static Decimal Min(Decimal val1, Decimal val2) {
            return Decimal.Min(val1, val2);
        }

        /*=====================================Log======================================
        **
        ==============================================================================*/
        //| <include path='docs/doc[@for="Math.Log1"]/*' />
        public static double Log(double a, double newBase) {
            return (Log(a) / Log(newBase));
        }

        // Sign function for VB.  Returns -1, 0, or 1 if the sign of the number
        // is negative, 0, or positive.  Throws for floating point NaN's.
        //| <include path='docs/doc[@for="Math.Sign"]/*' />
        [CLSCompliant(false)]
        public static int Sign(sbyte value)
        {
            if (value < 0) {
                return -1;
            }
            else if (value > 0) {
                return 1;
            }
            else {
                return 0;
            }
        }

        // Sign function for VB.  Returns -1, 0, or 1 if the sign of the number
        // is negative, 0, or positive.  Throws for floating point NaN's.
        //| <include path='docs/doc[@for="Math.Sign1"]/*' />
        public static int Sign(short value)
        {
            if (value < 0) {
                return -1;
            }
            else if (value > 0) {
                return 1;
            }
            else {
                return 0;
            }
        }

        // Sign function for VB.  Returns -1, 0, or 1 if the sign of the number
        // is negative, 0, or positive.  Throws for floating point NaN's.
        //| <include path='docs/doc[@for="Math.Sign2"]/*' />
        public static int Sign(int value)
        {
            if (value < 0) {
                return -1;
            }
            else if (value > 0) {
                return 1;
            }
            else {
                return 0;
            }
        }

        //| <include path='docs/doc[@for="Math.Sign3"]/*' />
        public static int Sign(long value)
        {
            if (value < 0) {
                return -1;
            }
            else if (value > 0) {
                return 1;
            }
            else {
                return 0;
            }
        }

        //| <include path='docs/doc[@for="Math.Sign4"]/*' />
        public static int Sign(float value)
        {
            if (value < 0) {
                return -1;
            }
            else if (value > 0) {
                return 1;
            }
            else if (value == 0) {
                return 0;
            }
            throw new ArithmeticException("Arithmetic_NaN");
        }

        //| <include path='docs/doc[@for="Math.Sign5"]/*' />
        public static int Sign(double value)
        {
            if (value < 0) {
                return -1;
            }
            else if (value > 0) {
                return 1;
            }
            else if (value == 0) {
                return 0;
            }
            throw new ArithmeticException("Arithmetic_NaN");
        }

        //| <include path='docs/doc[@for="Math.Sign6"]/*' />
        public static int Sign(Decimal value)
        {
            if (value < 0) {
                return -1;
            }
            else if (value > 0) {
                return 1;
            }
            else {
                return 0;
            }
        }

        //| <include path='docs/doc[@for="Math.BigMul"]/*' />
        public static long BigMul(int a, int b) {
            return ((long)a) * b;
        }

        //| <include path='docs/doc[@for="Math.DivRem"]/*' />
        public static int DivRem(int a, int b, out int result) {
            result = a % b;
            return a / b;
        }

        //| <include path='docs/doc[@for="Math.DivRem1"]/*' />
        public static long DivRem(long a, long b, out long result) {
            result = a % b;
            return a / b;
        }
    }
}