Here is the logic behind this comment-all-out method: type all the lines and then comment them all. After that, we release one line at a time to debug. We use the Black-Scholes' call option as an example in the following case:
Launch Python, click on File | New Window Ctrl + N. Generate the five lines of code mentioned in step 3. We include several bugs on purpose.
Click on File and save it.
Comment out the entire program by using a pair of triple quotation marks. Since we need some output, we add a return line as follows:
def bs_call(S,X,T,r,sigma): """ d1 = (lo(S/X)+(r+sigma*sigma/2.)*T)/(sigma*sqrt(T)) d2 = d1-sigmasqrt(T) return SCN(d1)-X*exp(-r*T)*CND(d2) """ return (X)
Again, click on Run and then Run from module F5. We will see that the following output appears:
>>>===========RESTART ===============
We test it by using any set of input values as follows:
>>>bs_call(40,40,0.5,0.1,0.2) 40 >>>bs_call...