Known bugs and typos

Quite a few bugs have been discovered in the code examples of the book. These have all been corrected in the source code files available here, but they are still present in the published version:

Chapter 3

• In the last code block on page 24, the first line of the interactive session is ‘l[0] =2’. But the variable ‘l’ has not been defined, and this line has nothing to do with the rest of the example.

Chapter 4

• In the code block on page 41, an argument is missing in the call to the function ‘amount’. The call should read something like ‘a0, r = amount(7,r)’.
• There are some minor errors in the interactive session on page 44-45, which illustrates the use of default arguments. Specifically, the third call to ‘somefunc’ is listed with the wrong output and an incorrect comment.

Chapter 5

• In the second code block on page 76, in line ‘n = years(P, 2*P, p)’, the variable ‘p’ is not defined. It should be replaced by ‘r’.
• Similar to the above, in the second code block on page 77, the f-string in the print statement includes the variable ‘p’ at the end. But ‘p’ is not defined, and should be replaced by ‘r’
• On page 78, in the code block that starts on page 77, the assert statement uses the wrong variable names. ‘A0’ should be replace by ‘P’ and ‘p’ by ‘r’.

Chapter 6

• In the block in the middle of page 84, the variable ‘y’ is never defined. For the loop to work this needs to be initialized to an array having the same length as ‘x’.
• In the formula at the top of page 86, the bounds for x are first defined in the formula and then again on the next line. The definition in the formula makes most sense, and is consistent with the code.
• On page 88, a comment in the code block says ‘[tmin, tmax,… ]’ where it should have been ‘[xmin, xmax,… ]’.
• In the last code block on page 90, in the line ‘t = np.linspace(0, 8, 201)’, ‘t’ should be replaced by ‘x’.
• In the code blocks on page 99, continued from page 98, the prefix ‘np.’ is missing in front of ‘zeros’, ‘asarray’ and other NumPy functions.
• In the last code block on page 99, in line ‘a[a < 0] = a.max() # if a[i]<10, set a[i]=10’, the comment does not match the code. The code will replace all entries of ‘a’ below 0, but the comment says below 10.

Chapter 7

• On page 102, there should be quotes around the word ‘Berlin’ in the code block in the middle.
• On page 103, in the second code block, the line ‘print(f’The {city} temperature is temps{city}’)’ should be ‘print(f’The {city} temperature is {temps[city]})’
• On page 103, the print statement in the second-to-last code block is missing parentheses.
• On page 106, missing parantheses in the print statement in the last code block.
• On page 109, the ‘:’ that appear on the first lines of the first interactive example should not be there. Further down in the same example the print statements are missing parentheses.
• In the last code block on page 111, there should be quotes around 5 in the line ‘s2 = s.replace(s[18],5)’ to make the argument a string (‘5’) rather than an integer.

Chapter 8

• On page 118, in class ‘Barometric1’ in the second code block, the gas constant ‘R’ has the wrong value
• The wrong class name is used in the interactive session at the bottom of page 121. To be consistent with the code above, ‘Account’ must be replaced by ‘BankAccount’. For the session to work one should also include an import of ‘BankAccount’.
• In the same interactive session example, the print statement is missing parentheses.
• In the ‘BankAccountP’ example on page 122 there are multiple bugs:
  • The constructor includes the line ‘self._last_name = name’, which should be ‘self._last_name = last_name’ to be consistent with the argument list.
  • In the method ‘print_info’, the underscore is missing in front of all the instance variables, ‘first = self.first_name’ should be ‘first = self._first_name’, etc.
  • In the same method, a local variable is named ‘bal’, but in the next line the ‘balance’ is used, which is not defined.
• On page 126, the first line of the second code block, ‘from tmp import *’, should be removed.

Chapter 9

• In the definition of the Trapezoidal class on page 144, the prefix ‘np.’ is missing in front of the NumPy functions ‘zeros’ and ‘linspace’.
• In the Simpson class on page 144, the print statement is missing parentheses.

The list is probably incomplete. If you find bugs or typos that are not on this list, please send an email to sundnes@simula.no