Comments on Bill the Lizard: SICP Exercise 1.22: Timed Prime Test

The 'runtime' function is available in DrR...

2011-06-18T08:27:02.968-04:00

The 'runtime' function is available in DrRacket with http://www.neilvandyke.org/racket-sicp/

pbewig, Good suggestion. That is one of the optio...

2010-02-05T21:11:12.577-05:00

pbewig,
Good suggestion. That is one of the options that I looked at when I realized 'runtime' wasn't going to work. I'd hoped I'd be able to rewrite 'timed-prime-test' using 'time', but I couldn't figure out a clean way to conditionally report the timing stats only if the input was prime. The only way I could get it to work was to test once for primality, then test again wrapped in a 'time' call.

Troy, You have a sharp eye! The first set of erro...

2010-02-05T20:49:33.771-05:00

Troy,
You have a sharp eye! The first set of errors were all my bad, since I just copied the first row to fill in the table, then somehow forgot to correct that group. In the second set (in the 10^15 group), the numbers were actually too big for Excel, where I had saved them temporarily, so the values were rounded off. Still, that was my fault for blindly copying and pasting them into my blog editor. I really appreciate the correction.

Use the time function. See http://programmingpraxis.codepad.org/b4BtoRwq.

I think you have some transcription errors in your...

2010-02-05T19:19:55.161-05:00

I think you have some transcription errors in your table. You list the first three primes after 10**10 as

10000000019
10000000019
10000000019

Also, all of the "primes" after 10**15 are divisible by 10.