title: How to disable a mat Input field based on the value of a mat radio button?
body: <p>I have a 'mat-radio-group' in my form which has 2 'mat-radio-button's with values "yes" and "no". </p>
  
  <p>I want to use these values to enable or disable another input field (simple matInput) depending on what the user selects. </p>
  
  <p>I would also like to disable the matInput by default (before the user check "yes" or "no" from the radio group). </p>
  
  <p>I'm using Angular reactive forms and have setup form control names for these inputs. </p>
  
  <p>Imagine the formGroup name is "myForm". </p>
  
  <p>Below is the code I have in my template:</p>
  
  <pre><code>&lt;mat-radio-group formControlName="myRadio"&gt;
            &lt;mat-radio-button value="yes" required&gt;Yes&lt;/mat-radio-button&gt;
            &lt;mat-radio-button value="no" required checked&gt;No&lt;/mat-radio-button&gt;
  &lt;/mat-radio-group&gt;
  
  &lt;mat-form-field&gt;
            &lt;input matInput formControlName="myInput" /&gt;
  &lt;/mat-form-field&gt;
  </code></pre>