function MyCalc(){
  //First, let's make sure the values entered are actually numbers
  if (isNaN(document.forms['formCalc'].stake.value)) {
	  alert("Please enter a numeric value in the Stake box");
	  document.forms['formCalc'].stake.value = 0;
  }	
  if (isNaN(document.forms['formCalc'].back_odds.value)) {
	  alert("Please enter a numeric value in the Back Odds box");
	  document.forms['formCalc'].back_odds.value = 0;
  }	
  if (isNaN(document.forms['formCalc'].lay_odds.value)) {
	  alert("Please enter a numeric value in the Lay Odds box");
	  document.forms['formCalc'].lay_odds.value = 0;
  }	
  if (isNaN(document.forms['formCalc'].back_comm.value)) {
	  alert("Please enter a numeric value in the Back Commission box");
	  document.forms['formCalc'].back_comm.value = 0;
  }	
  if (isNaN(document.forms['formCalc'].lay_comm.value)) {
	  alert("Please enter a numeric value in the Lay Commission box");
	  document.forms['formCalc'].lay_comm.value = 0;
  }	
  backReturn = 0;
  backReturn = parseFloat(document.forms['formCalc'].back_odds.value) * parseFloat(document.forms['formCalc'].stake.value)-(parseFloat(document.forms['formCalc'].back_comm.value) * ((parseFloat(document.forms['formCalc'].back_odds.value)-1)*parseFloat(document.forms['formCalc'].stake.value))/100) - parseFloat(document.forms['formCalc'].snr.value);
  //backReturn = backReturn.toFixed(2);
  if (isNaN(backReturn))
    document.forms['formCalc'].back_return.value = 0;
  else if (backReturn == Infinity)
    document.forms['formCalc'].back_return.value = 0;
  else {
    //backReturn=Math.round(backReturn*100)/100.0
    document.forms['formCalc'].back_return.value = backReturn;
  }
  
  layStake = 0;
  layStake = parseFloat(document.forms['formCalc'].back_return.value) / (parseFloat(document.forms['formCalc'].lay_odds.value) - parseFloat(document.forms['formCalc'].lay_comm.value) / 100);
  //layStake = layStake.toFixed(2);
  if (isNaN(layStake))
    document.forms['formCalc'].lay_stake.value = 0;
  else if (layStake == Infinity)
    document.forms['formCalc'].lay_stake.value = 0;
  else {
  //layStake=Math.round(layStake*100)/100.0
  document.forms['formCalc'].lay_stake.value = layStake;
  }
  
  layRisk = 0;
  layRisk = parseFloat(document.forms['formCalc'].lay_stake.value) * (parseFloat(document.forms['formCalc'].lay_odds.value) - 1);
  //layRisk = layRisk.toFixed(2);
  if (isNaN(layRisk))
    document.forms['formCalc'].lay_risk.value = 0;
  else if (layRisk == Infinity)
    document.forms['formCalc'].lay_risk.value = 0;
  else {
  //layRisk=Math.round(layRisk*100)/100.0
  document.forms['formCalc'].lay_risk.value = layRisk;
  }
  
  backProfit = 0;
  backProfit = parseFloat(document.forms['formCalc'].back_return.value) - parseFloat(document.forms['formCalc'].lay_risk.value);
  //backProfit = backProfit.toFixed(2);
  if (isNaN(backProfit))
    document.forms['formCalc'].back_profit.value = 0;
  else if (backProfit == Infinity)
    document.forms['formCalc'].back_profit.value = 0;
  else {
  //backProfit=Math.round(backProfit*100)/100.0
  document.forms['formCalc'].back_profit.value = backProfit;
  }
  
  layProfit = 0;
  layProfit = parseFloat(document.forms['formCalc'].lay_stake.value) * (100 - parseFloat(document.forms['formCalc'].lay_comm.value)) / 100;
  //layProfit = layProfit.toFixed(2);
  if (isNaN(layProfit))
    document.forms['formCalc'].lay_profit.value = 0;
  else if (layProfit == Infinity)
    document.forms['formCalc'].lay_profit.value = 0;
  else {
  //layProfit=Math.round(layProfit*100)/100.0
    document.forms['formCalc'].lay_profit.value = layProfit;
  }
  
  backReturnRound = backReturn.toFixed(2);
  layStakeRound = layStake.toFixed(2);
  layRiskRound = layRisk.toFixed(2);
  backProfitRound = backProfit.toFixed(2);
  layProfitRound = layProfit.toFixed(2);
    document.forms['formCalc'].back_return.value = backReturnRound;
  document.forms['formCalc'].lay_stake.value = layStakeRound;
  document.forms['formCalc'].lay_risk.value = layRiskRound;
  document.forms['formCalc'].back_profit.value = backProfitRound;
    document.forms['formCalc'].lay_profit.value = layProfitRound;
}