1.For converting from text box text to double you should use
double.TryParse()
method like below:
double number =0.0;
double.TryParse(T.Trim(), out number);
var AB= number * Simulation.B)
2.You could also test the result of the
TryParse
and if the conversion is not OK to use a default value like below:
double number =0.0;
if(double.TryParse(T.Trim(), out number) == false)
number = 1.0;
var AB= number * Simulation.B)