SEECBC/FrontEnd/components/playground/gradient-descent/gradient-descent.ts

import { SingleVarFunction } from './functions'

export interface Point {
  x: number
  y: number
}

export interface OneStepInfo {
  gradient: number
  deltaX: number
  resultPoint: Point
}

export class GradientDescent {
  private targetFunction: SingleVarFunction
  private currentPoint: Point = { x: 0, y: 0 }

  constructor(targetFunction: SingleVarFunction, initialPoint: Point) {
    this.targetFunction = targetFunction
    this.currentPoint = initialPoint
  }

  oneStep(learningRate: number): OneStepInfo {
    const x = this.currentPoint.x
    const gradient = this.targetFunction.df(x)
    const deltaX = -learningRate * gradient
    const resultX = x + deltaX
    const resultPoint = { x: resultX, y: this.targetFunction.f(resultX) }

    this.currentPoint = resultPoint

    return { gradient, deltaX, resultPoint }
  }
}