Angular FormArray

formarray.ts

    const ctrl = this.myForm.controls['rows'];
    ctrl.controls.forEach((field) => {
      const col1 = parseInt(field.get('col1').value, 10);
      const col2 = parseInt(field.get('col2').value, 10);
      const sum = col1 + col2;
      // How to set these values to col3?
      // Doesn't work: field.get('col3').setValue(sum);
    });

    public createForm() {
        this.myForm = this.fb.group({
          name: ['', Validators.required],
        });
    }

    public pushRowItems(items) {
        this.myForm.addControl('rows', this.fb.array([items]));
    }

    public initItemRows() {
        return this.fb.group({
          col1: 0,
          col2: 0,
          col3: 0,
        });
    }

    public ngOnInit() {
    this.createForm();
    this.pushRowItems(this.initRowItems());
    }