title: What is the simplest way to constraint a built-in function's output in Mathematica? say let Sin returns only odd numbers?
body: <p>For example, for a <strong>built-in</strong> function in Mathematica, f,  originally f[1] gives {1,2,3}, but I want to let Mathematica gives only {1,3}. A simple method for <strong>rewritting</strong> f is desired. I don't want to define a new function or totally rewrite f or just dealing with original f's outputs. I want to rewite f.</p>
  
  <p>Thanks. :)</p>