[HN Gopher] We verify the correctness of a spreadsheet engine
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       We verify the correctness of a spreadsheet engine
        
       Author : breckognize
       Score  : 41 points
       Date   : 2024-09-11 15:25 UTC (4 days ago)
        
 (HTM) web link (rowzero.io)
 (TXT) w3m dump (rowzero.io)
        
       | gamegoblin wrote:
       | I had written this comment[0] about our pattern here a few months
       | ago and we decided to turn it into a full blog post.
       | 
       | It's crazy how many weird bugs you can detect with such a trivial
       | method.
       | 
       | For applications like a spreadsheet that have a million
       | overlapping features, it's impossible to manually write unit
       | tests for every combination of features, so randomized tests do a
       | lot of heavy lifting.
       | 
       | [0] https://news.ycombinator.com/item?id=40876726
        
         | ForOldHack wrote:
         | Unless your spread sheet can calculate unit tests, then it can
         | combine tests in combinatorial fashion, and build Weinerstrauss
         | test monsters. ( I am kidding on this last point, Spreadsheets
         | will never operate in fractional dimensions. )
         | 
         | If, of course, you can calculate rule 110/124, then your spread
         | sheet can be considered Turing complete.
         | 
         | "With LAMBDA, Excel has become Turing-complete. You can now, in
         | principle, write any computation in the Excel formula
         | language.Jan 25, 2021"."
         | 
         | The only caveat to Excel being Turing-complete is that it will
         | never ever display the results properly.
        
           | ForOldHack wrote:
           | I tested Excel, and even early versions can calculate Rule
           | 124. Now I have loaded it down with rotating a right triangle
           | in 1/n radians. ( The right triangle has sides e+1/Pi and
           | Pi+1/e. )...
           | 
           | Maybe your spreadsheet will do better?
        
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