function valNumericStr(strFieldName,strValue,intBlankFlag,intMsgFlag){if(strValue.length<1){if(intBlankFlag==0){if(intMsgFlag==1)alert("Please enter a value for "+strFieldName+".");return false;}}else{var decPtAt=0;for(var i=0;i<strValue.length;i++){var localChar=strValue.charAt(i);if(localChar<"0"||localChar>"9"){if(localChar=="."&&decPtAt==0){decPtAt=i+1;}else{if(intMsgFlag==1)alert("Please remove the '"+localChar+"' character from "+strFieldName+".");return false;}}}}return true;}
function formatFloat(expr,decplaces){var str=""+Math.round(eval(expr)*Math.pow(10,decplaces));while(str.length<=decplaces){str="0"+str;}var decpoint=str.length-decplaces;return str.substring(0,decpoint)+"."+str.substring(decpoint,str.length);}
function periodizeRate(annualRate,compoundPerYear,decimalFlag){if(decimalFlag==1)periodicRate=annualRate/(compoundPerYear*100);else periodicRate=annualRate/compoundPerYear;return periodicRate;}
function switchFunction(){var curPayment,intTerm,answer;var pctARate,pctPRate,curBalance;curBalance=document.calculator.balance.value;if(valNumericStr("balance",curBalance,0,1)==false)curBalance=0.00;else curBalance=parseFloat(curBalance);pctARate=document.calculator.arate.value;if(valNumericStr("interest rate",pctARate,0,1)==false)pctARate=0.00;else pctARate=parseFloat(pctARate);pctPRate=periodizeRate(pctARate,12,1);curPayment=document.calculator.payment.value;intTerm=document.calculator.term.value;if(curPayment=="see below"&&valNumericStr("months until balance is paid",intTerm,0,1)==true){answer=calcPayments(curBalance,intTerm,pctPRate);document.calculator.answer.value="$"+formatFloat(answer,2)+" every month";}else if(intTerm=="see below"&&valNumericStr("payment per month",curPayment,0,1)==true){answer=calcTerm(curBalance,curPayment,pctPRate);document.calculator.answer.value=answer+" months";}else{alert("Please enter a value for either 'payment per month' or 'months until paid', not both.");return;}}
function calcTerm(balance,payment,pRate){var interest,paymentCount;paymentCount=0;while(balance>0.00){interest=parseInt(balance)*pRate;if(parseInt(interest,10)>payment){alert("Your payments are not enough to cover the accumulated interest. Try increasing the payments.");return"infinite";}balance=parseInt(balance,10)+parseInt(interest,10)-parseInt(payment,10);paymentCount=paymentCount+1;}return paymentCount;}
function calcPayments(balance,term,pRate){var temp1,paymentValue;temp1=Math.pow((pRate+1),term);paymentValue=(balance/((1/pRate)-(1/(pRate*temp1))));return parseFloat(paymentValue);}