mat/gradfn/addscalar.go
// Copyright 2019 spaGO Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.
package gradfn
import (
"fmt"
"github.com/nlpodyssey/spago/mat"
)
// AddScalar is an operator to perform element-wise addition over two values.
type AddScalar[O mat.Tensor] struct {
x1 O
x2 O // scalar
}
// NewAddScalar returns a new AddScalar Function.
func NewAddScalar[O mat.Tensor](x1, x2 O) *AddScalar[O] {
return &AddScalar[O]{
x1: x1,
x2: x2,
}
}
// Operands returns the list of operands.
func (r *AddScalar[O]) Operands() []mat.Tensor {
return []mat.Tensor{r.x1, r.x2}
}
// Forward computes the output of the function.
// It doesn't backward on the scalar value x2.
func (r *AddScalar[O]) Forward() (mat.Tensor, error) {
return r.x1.Value().(mat.Matrix).AddScalar(r.x2.Value().Item().F64()), nil
}
// Backward computes the backward pass.
func (r *AddScalar[O]) Backward(gy mat.Tensor) error {
if !mat.SameDims(r.x1.Value().(mat.Matrix), gy.(mat.Matrix)) {
return fmt.Errorf("fn: matrices have incompatible dimensions")
}
if r.x1.RequiresGrad() {
r.x1.AccGrad(gy)
}
if r.x2.RequiresGrad() {
gx := gy.(mat.Matrix).Sum()
r.x2.AccGrad(gx)
}
return nil
}