private void CalculateSolution(IntegralMethod method, out double?solution)
{
try
{
double a = Convert.ToDouble(textBox1.Text),
b = Convert.ToDouble(textBox2.Text);
int n = Convert.ToInt32(numericUpDown1.Value);
solution = func.CalculateDeterminedIntegral(method, a, b, n);
}
catch (InvalidCastException exp)
{
solution = null;
MessageBox.Show(exp.Message);
}
}