Locating child of a nearby ancestor with jQuery
I would make the link between the 2 implicit.

&lt;a href="#mdpdate" id="startdatecalicon" class="dpicon"&gt;

Then the code is 

$(".dpicon").click(function(){
  $( this.href ).focus()
}


It is a creative (ab)use of href, but it still follows the spirit in my mind.

If you have the luxury of going HTML5, you can go with a data attribute.

&lt;a href="#" id="startdatecalicon" class="dpicon" data-dpicker="#mdpdate"&gt;

Then the code is 

$(".dpicon").click(function(){
  $( this.getAttribute( "data-dpicker" ) ).focus()
}