Method _trainPattern

src/neural-network.js:490–504

* * @param input * @param target

(input, target, logErrorRate)

   * @param target
   */
  _trainPattern(input, target, logErrorRate) {

    // forward propagate
    this.runInput(input);

    // back propagate
    this.calculateDeltas(target);
    this._adjustWeights();

    if  (logErrorRate) {
      return mse(this.errors[this.outputLayer]);
    } else {
      return null;
    }
  }

  /**
   *