Refreshing the formula field based on text field using Trigger.

Refreshing the fields based on text field(FX Rate to usd) parent to child will refresh(Calculations using formula field) parent.

Parent to child to parent updation using trigger.

Trigger:-

trigger Fieldupdations on Opportunity_Margin_Template__c (after update) {
List<Opportunity_Margin_Template__c> templist = new List<Opportunity_Margin_Template__c>();
List<Opportunity_Template_Task__c> templatetasklist = new List<Opportunity_Template_Task__c>();
set<id> setid = new set<id>();
for(Opportunity_Margin_Template__c margin: Trigger.new)
{
 setid.add(margin.id);
}
List<Opportunity_Margin_Template__c> tasklist = [select Id,Name,Template_Save_as__c,FX_Rate_to_USD__c from Opportunity_Margin_Template__c
                                                 where id in:setid];
templatetasklist =[select id, Cost_Hr__c,Opportunity_Margin_Template__c from   Opportunity_Template_Task__c where  Opportunity_Margin_Template__r.id In : setid];                                        
for(Opportunity_Margin_Template__c temp: tasklist)
{
 if(temp.FX_Rate_to_USD__c!=Trigger.oldmap.get(temp.Id).FX_Rate_to_USD__c)
 {
   templist.add(temp);
 }
}
update templatetasklist ;      
update templist;                                                                                
             

}