function calculate() {
                
                    // check input data validity (numeric values)
                    if((new Number(document.all["odds1"].value)).toString() == "NaN") {
                        alert("Invalid Odds numerator value format");
                        document.all["odds1"].value = "0";
                        document.all["percentage"].value = "0.0";
                        document.all["priceline"].value = "0.0";                        
                        return;
                    }

                    if((new Number(document.all["odds2"].value)).toString() == "NaN") {
                        alert("Invalid Odds denominator value format");
                        document.all["odds2"].value = "0";
                        document.all["percentage"].value = "0.0";
                        document.all["priceline"].value = "0.0";                        
                        return;
                    }

                    // check input data validity (positive values only)
                    if(document.all["odds1"].value < 0) {
                        alert("Invalid Odds numerator value");
                        document.all["odds1"].value = "0";
                        document.all["percentage"].value = "0.0";
                        document.all["priceline"].value = "0.0";                        
                        return;
                    }

                    if(document.all["odds2"].value < 0) {
                        alert("Invalid Odds denominator value");
                        document.all["odds2"].value = "0";
                        document.all["percentage"].value = "0.0";
                        document.all["priceline"].value = "0.0";                        
                        return;
                    }

                    if((document.all["odds1"].value > 0) && (document.all["odds2"].value > 0)) {
						document.all["priceline"].value = Math.round(((parseInt(document.all["odds1"].value) / parseInt(document.all["odds2"].value)) + 1 ) * 100) / 100;
						document.all["percentage"].value = Math.round((100 / document.all["priceline"].value) * 100) / 100;
                    } else {
                        document.all["percentage"].value = "0.0";
                        document.all["priceline"].value = "0.0";                        
                    }
                }