Talk:Pathological floating point problems: Difference between revisions
Talk:Pathological floating point problems (view source)
Revision as of 03:35, 30 April 2017
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:After some head-scratching I found https://www.mirrorservice.org/sites/www.bitsavers.org/pdf/ibm/1620/ which had a link to https://www.mirrorservice.org/sites/www.bitsavers.org/pdf/ibm/1620/C26-5876-2_FORTRAN_II_Mar65.pdf wherein after reading to page 24 (damn .pdf is image-only: no searchable text) I found the heading '''Source Program Control Card''' which is to precede the Fortran source, in the form <code>*ffkks</code> where ''ff'' is the size of the floating-point mantissa (2 to 28), ''kk'' the size of integers (2 to 10) and ''s'' is the memory size of 2, 4, 6 for 20,000 to 60,000 digits if it is to be not that of the current computer.
:I don't recall ever using this facility, as my major program at Auckland University for the 1620 was to write a simulator for the AMI computer (simulated on the IBM 1130) that had been used for teaching a first year course in applied mathematics in AMI machine code, leading to the calculation of functions and Chebyshev adjustment of those calculations. I have always wondered how the 1620 handled such functions (sine, cosine, etc) given different precisions, as there was no sign of different decks of cards for the subroutine library for different precisions, and the use of Chebyshev polynomials to "economise" the precision of a particular calculation via a power series depended very much on what precision was being employed and pursued. Perhaps, just slog through additional terms until they become small enough rather than a pre-determined sufficient number of terms. [[User:Dinosaur|Dinosaur]] ([[User talk:Dinosaur|talk]]) 03:31, 30 April 2017 (UTC)
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