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// Licensed to the .NET Foundation under one or more agreements.
// The .NET Foundation licenses this file to you under the MIT license.
using System.Runtime.CompilerServices;
using System.Runtime.Intrinsics;
namespace System.Numerics.Tensors
{
public static partial class TensorPrimitives
{
/// <summary>Searches for the number with the largest magnitude in the specified tensor.</summary>
/// <param name="x">The tensor, represented as a span.</param>
/// <returns>The element in <paramref name="x"/> with the largest magnitude (absolute value).</returns>
/// <exception cref="ArgumentException">Length of <paramref name="x" /> must be greater than zero.</exception>
/// <remarks>
/// <para>
/// The determination of the maximum magnitude matches the IEEE 754:2019 `maximumMagnitude` function. If any value equal to <see cref="IFloatingPointIeee754{TSelf}.NaN"/>
/// is present, the first is returned. If two values have the same magnitude and one is positive and the other is negative,
/// the positive value is considered to have the larger magnitude.
/// </para>
/// <para>
/// This method may call into the underlying C runtime or employ instructions specific to the current architecture. Exact results may differ between different
/// operating systems or architectures.
/// </para>
/// </remarks>
public static T MaxMagnitude<T>(ReadOnlySpan<T> x)
where T : INumberBase<T> =>
MinMaxCore<T, MaxMagnitudeOperator<T>>(x);
/// <summary>Computes the element-wise number with the largest magnitude in the specified tensors.</summary>
/// <param name="x">The first tensor, represented as a span.</param>
/// <param name="y">The second tensor, represented as a span.</param>
/// <param name="destination">The destination tensor, represented as a span.</param>
/// <exception cref="ArgumentException">Length of <paramref name="x" /> must be same as length of <paramref name="y" />.</exception>
/// <exception cref="ArgumentException">Destination is too short.</exception>
/// <exception cref="ArgumentException"><paramref name="x"/> and <paramref name="destination"/> reference overlapping memory locations and do not begin at the same location.</exception>
/// <exception cref="ArgumentException"><paramref name="y"/> and <paramref name="destination"/> reference overlapping memory locations and do not begin at the same location.</exception>
/// <remarks>This method effectively computes <c><paramref name="destination" />[i] = <typeparamref name="T"/>.MaxMagnitude(<paramref name="x" />[i], <paramref name="y" />[i])</c>.</remarks>
/// <remarks>
/// <para>
/// This method may call into the underlying C runtime or employ instructions specific to the current architecture. Exact results may differ between different
/// operating systems or architectures.
/// </para>
/// </remarks>
public static void MaxMagnitude<T>(ReadOnlySpan<T> x, ReadOnlySpan<T> y, Span<T> destination)
where T : INumberBase<T> =>
InvokeSpanSpanIntoSpan<T, MaxMagnitudeOperator<T>>(x, y, destination);
/// <summary>Computes the element-wise number with the largest magnitude in the specified tensors.</summary>
/// <param name="x">The first tensor, represented as a span.</param>
/// <param name="y">The second tensor, represented as a scalar.</param>
/// <param name="destination">The destination tensor, represented as a span.</param>
/// <exception cref="ArgumentException">Destination is too short.</exception>
/// <exception cref="ArgumentException"><paramref name="x"/> and <paramref name="destination"/> reference overlapping memory locations and do not begin at the same location.</exception>
/// <remarks>This method effectively computes <c><paramref name="destination" />[i] = <typeparamref name="T"/>.MaxMagnitude(<paramref name="x" />[i], <paramref name="y" />)</c>.</remarks>
/// <remarks>
/// <para>
/// This method may call into the underlying C runtime or employ instructions specific to the current architecture. Exact results may differ between different
/// operating systems or architectures.
/// </para>
/// </remarks>
public static void MaxMagnitude<T>(ReadOnlySpan<T> x, T y, Span<T> destination)
where T : INumberBase<T> =>
InvokeSpanScalarIntoSpan<T, MaxMagnitudeOperator<T>>(x, y, destination);
/// <summary>Operator to get x or y based on which has the larger MathF.Abs</summary>
internal readonly struct MaxMagnitudeOperator<T> : IAggregationOperator<T>
where T : INumberBase<T>
{
public static bool Vectorizable => true;
[MethodImpl(MethodImplOptions.AggressiveInlining)]
public static T Invoke(T x, T y) => T.MaxMagnitude(x, y);
[MethodImpl(MethodImplOptions.AggressiveInlining)]
public static Vector128<T> Invoke(Vector128<T> x, Vector128<T> y)
{
#if NET9_0_OR_GREATER
return Vector128.MaxMagnitude(x, y);
#else
if ((typeof(T) == typeof(float)) || (typeof(T) == typeof(double)))
{
Vector128<T> xMag = Vector128.Abs(x);
Vector128<T> yMag = Vector128.Abs(y);
return Vector128.ConditionalSelect(
Vector128.GreaterThan(xMag, yMag) | IsNaN(xMag) | (Vector128.Equals(xMag, yMag) & IsPositive(x)),
x,
y
);
}
return MaxMagnitudeNumberOperator<T>.Invoke(x, y);
#endif
}
[MethodImpl(MethodImplOptions.AggressiveInlining)]
public static Vector256<T> Invoke(Vector256<T> x, Vector256<T> y)
{
#if NET9_0_OR_GREATER
return Vector256.MaxMagnitude(x, y);
#else
if ((typeof(T) == typeof(float)) || (typeof(T) == typeof(double)))
{
Vector256<T> xMag = Vector256.Abs(x);
Vector256<T> yMag = Vector256.Abs(y);
return Vector256.ConditionalSelect(
Vector256.GreaterThan(xMag, yMag) | IsNaN(xMag) | (Vector256.Equals(xMag, yMag) & IsPositive(x)),
x,
y
);
}
return MaxMagnitudeNumberOperator<T>.Invoke(x, y);
#endif
}
[MethodImpl(MethodImplOptions.AggressiveInlining)]
public static Vector512<T> Invoke(Vector512<T> x, Vector512<T> y)
{
#if NET9_0_OR_GREATER
return Vector512.MaxMagnitude(x, y);
#else
if ((typeof(T) == typeof(float)) || (typeof(T) == typeof(double)))
{
Vector512<T> xMag = Vector512.Abs(x);
Vector512<T> yMag = Vector512.Abs(y);
return Vector512.ConditionalSelect(
Vector512.GreaterThan(xMag, yMag) | IsNaN(xMag) | (Vector512.Equals(xMag, yMag) & IsPositive(x)),
x,
y
);
}
return MaxMagnitudeNumberOperator<T>.Invoke(x, y);
#endif
}
public static T Invoke(Vector128<T> x) => HorizontalAggregate<T, MaxMagnitudeOperator<T>>(x);
public static T Invoke(Vector256<T> x) => HorizontalAggregate<T, MaxMagnitudeOperator<T>>(x);
public static T Invoke(Vector512<T> x) => HorizontalAggregate<T, MaxMagnitudeOperator<T>>(x);
}
}
}
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