tag:blogger.com,1999:blog-8216971263350849959.post6469153692010563188..comments2023-08-07T16:41:49.660+02:00Comments on Die Klimazwiebel: Coding errors - how many errors are on average in a lengthy code?eduardohttp://www.blogger.com/profile/17725131974182980651noreply@blogger.comBlogger4125tag:blogger.com,1999:blog-8216971263350849959.post-28203180586525479592011-08-16T12:38:12.765+02:002011-08-16T12:38:12.765+02:00This issue became important in connection with Edw...This issue became important in connection with Edward Teller's 'Star Wars', where on receipt of a signal of an approaching Russian missile, a parabolic mirror would be launched into space and aimed, so that the X-rays emitted by an exploding H-bomb would be focused on the travelling missile. One of the many technical issues was that the device involved some millions of lines of computer code, and could not be tested in advance. One computer expert said that the maximum number of lines of untested code without a bug was about 9; hence the probability of correct functioning was very low. In spite of such unanimous expert criticisms, the 'Star Wars' project had Reagan's support. Worse, at the Rekjavik conference with Gorbachov, negotiations broke down because the Russians insisted that the USA abandon the project. The interaction of fantasy with hardware has been particularly important in the modern period.Jerome Ravetzhttp://www.jerryravetz.co.uknoreply@blogger.comtag:blogger.com,1999:blog-8216971263350849959.post-59127067451344880852011-08-10T15:41:34.267+02:002011-08-10T15:41:34.267+02:00Hans, I'd note that the Stackoverflow discussi...Hans, I'd note that the Stackoverflow discussion was closed as 'Not a real question', and that I think is an accurate summary.<br /><br />I'd classify it as 'thinking like an accountant', as, just for starters, how will you ever get anyone to agree on exactly what constitutes an 'error'?Chucklesnoreply@blogger.comtag:blogger.com,1999:blog-8216971263350849959.post-1143717877903015742011-07-21T10:29:08.786+02:002011-07-21T10:29:08.786+02:00The number of errors is not necessarily a particul...The number of errors is not necessarily a particularly useful measure as the nature their consequences varies greatly. Some coding errors may lead to occasional failures to produce any results, while others lead to erroneous results.<br /><br />When we are mainly interested in the correctness of the results that have been obtained (rather than in the certainty that every attempt gives results) it may be more effective and in some cases sufficient to verify the results in some external way over a wide enough range of inputs. That approach may leave many errors in the code, but still provide enough certainty that the results are correct or close enough to correct for the actual use the results. On the other hand total lack of coding errors would not be of much help if a model has been built based on erroneous physics or mathematics (in the mathematics I include the validity of the numerical methods).Pekka Pirilähttp://www.pirila.fi/energynoreply@blogger.comtag:blogger.com,1999:blog-8216971263350849959.post-43062339550611511072011-07-20T12:28:54.210+02:002011-07-20T12:28:54.210+02:00Well, Steve Easterbrook comes to mind (University ...Well, Steve Easterbrook comes to mind (University of Toronto, http://www.easterbrook.ca/steve/). His blog suggests, that there has been a master thesis by a Jon Pipitone on the topic. Easterbrook blogged a preliminary number of 0.03 defects/KLoC for the "Met Office Hadley's Centre's Unified Model" and compares that number to the 0.1 defects/KLoC for the space shuttle flight software.OBothenoreply@blogger.com