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46 lines
1.7 KiB
Swift
46 lines
1.7 KiB
Swift
//===--- DifferentiationUtilities.swift -----------------------*- swift -*-===//
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//
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// This source file is part of the Swift.org open source project
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//
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// Copyright (c) 2014 - 2019 Apple Inc. and the Swift project authors
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// Licensed under Apache License v2.0 with Runtime Library Exception
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//
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// See https://swift.org/LICENSE.txt for license information
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// See https://swift.org/CONTRIBUTORS.txt for the list of Swift project authors
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//
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//===----------------------------------------------------------------------===//
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//
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// Utilities for creating differentiable functions, debugging, and customizing
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// derivatives.
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//
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//===----------------------------------------------------------------------===//
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import Swift
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//===----------------------------------------------------------------------===//
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// Derivative customization
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//===----------------------------------------------------------------------===//
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/// Returns `x` like an identity function. When used in a context where `x` is
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/// being differentiated with respect to, this function will not produce any
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/// derivative at `x`.
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@inlinable
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@inline(__always)
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@_semantics("autodiff.nonvarying")
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public func withoutDerivative<T>(at x: T) -> T {
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x
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}
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//===----------------------------------------------------------------------===//
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// Diagnostics
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//===----------------------------------------------------------------------===//
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@_silgen_name("_fatalErrorForwardModeDifferentiationDisabled")
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public func _fatalErrorForwardModeDifferentiationDisabled() -> Never {
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fatalError("""
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JVP does not exist. Use \
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'-Xfrontend -enable-experimental-forward-mode-differentiation' to enable \
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differential-first differentiation APIs.
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""")
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}
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