Disabled attribute not working on pattern

I'm using matInput and pattern for numbers and dots only

 <mat-form-field>
      <mat-label>Table Number</mat-label>
      <input matInput placeholder="Enter Table Number"
      pattern="^\d+(\.\d+)*$"  [(ngModel)]="newStudy.tableNo">             
  </mat-form-field>
  
  
  <input type="button" class="body-popup-btn" value="Save" [disabled]="!pattern" (click)="onSubmitClick()" style="background: #1d5f93;">

But the button not getting enabled again even if the pattern is correct.

Need quick solution for this !!!!