projekt:rudel:grovinventering:riemann
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projekt:rudel:grovinventering:riemann [2020/11/06 15:59] – created pontus | projekt:rudel:grovinventering:riemann [2021/05/27 19:39] (current) – pontus | ||
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**Signifikans: | **Signifikans: | ||
- | **Historia: | + | **Historia: |
- | **Donator: | + | **Donator: |
+ | |||
+ | **Tillbehör: | ||
+ | |||
+ | **Kontaktperson(er): | ||
+ | |||
+ | Länkar till Dennis hemsidor (som omnämner Riemann och visar bilder): | ||
+ | | ||
+ | * http:// | ||
+ | |||
+ | Utvalda bilder: | ||
+ | * http:// | ||
+ | * http:// | ||
+ | * http:// | ||
+ | |||
+ | Länk till UNT om utställningen på gustavianum: | ||
+ | * https:// | ||
+ | |||
+ | Plakat som användes vid utställningen "Tre ton minidatorer": | ||
+ | * {{ : | ||
+ | * {{ : | ||
+ | * {{ : | ||
+ | |||
+ | Information från Dennis: | ||
+ | |||
+ | < | ||
+ | Information about " | ||
+ | =========================== | ||
+ | |||
+ | |||
+ | (I) Machine Specifications. | ||
+ | |||
+ | CRAY YMP-EL4/ | ||
+ | (serial number: | ||
+ | |||
+ | The YMP-EL4/ | ||
+ | a maximum speed of 532 million operations per second. | ||
+ | |||
+ | 4 processors | ||
+ | 1 Gigabyte (1024 Megabytes) of memory for use in codes | ||
+ | 24 Gigabyte disk storage | ||
+ | |||
+ | Operated: | ||
+ | by Prof. Dennis Hejhal' | ||
+ | | ||
+ | |||
+ | Total Purchase Price: | ||
+ | | ||
+ | all paid for via a grant from NFR, i.e. current-day VR) | ||
+ | |||
+ | Donated to the Update Computer Club: mid-April 2001 | ||
+ | |||
+ | Machine age in 1996: about 4 years old | ||
+ | |||
+ | Previous Owner: | ||
+ | |||
+ | Software: | ||
+ | | ||
+ | |||
+ | Operating System: | ||
+ | |||
+ | Clock period: 30 nanoseconds | ||
+ | |||
+ | |||
+ | ------------------------------------------------------------- | ||
+ | |||
+ | The machine' | ||
+ | a peak performance per processor of 4 floating point | ||
+ | operations per clock period, which equates to 133 megaflops | ||
+ | (i.e., 133 million floating point operations per second). | ||
+ | |||
+ | Programs could also be run utilizing all 4 processors | ||
+ | in parallel. | ||
+ | a) Cray microtasking/ | ||
+ | parallelism of do-loops]; | ||
+ | b) PVM and MPT [for " | ||
+ | |||
+ | Used in parallel, the theoretical maximum speed was thus 532 | ||
+ | megaflops. In practice, on a good parallel code with lots of | ||
+ | numerical calculation (as opposed to i/o), Riemann ran about | ||
+ | 10% faster than one CRAY-XMP processor, and frequently as fast | ||
+ | as one (mainframe) YMP processor. | ||
+ | |||
+ | |||
+ | The following "per processor" | ||
+ | 1990s-era parallel-vector machines manufactured by Cray: | ||
+ | |||
+ | XMP - 8.5 nanosecond (117 Mhz) clock, 2 results per clock: | ||
+ | YMP - 6.0 nanosecond (166 Mhz) clock, 2 results per clock: | ||
+ | J90 -10.0 nanosecond (100 Mhz) clock, 2 results per clock: | ||
+ | C90 - 4.16 nanosecond (240 Mhz) clock, 4 results per clock: | ||
+ | EL - 30.0 nanosecond (33 Mhz) clock, 4 results per clock: | ||
+ | |||
+ | Two machines here give 4 results per clock: | ||
+ | vector pipes (all vectors run at 2 results per clock); | ||
+ | gets this from 4 independent functional units. | ||
+ | |||
+ | |||
+ | |||
+ | |||
+ | (II) Scientific Information. | ||
+ | |||
+ | During 1996-2001, Riemann was heavily used in Dennis Hejhal' | ||
+ | University research group on analytic number theory and quantum chaos. | ||
+ | |||
+ | Notable experiments carried out on Riemann include: | ||
+ | |||
+ | a) The detailed calculation of numerous quantum " | ||
+ | linked to either prime number symmetries or lattices in negatively curved | ||
+ | space. | ||
+ | the states of highest energy in each context. | ||
+ | |||
+ | b) The first-ever calculation of what are called " | ||
+ | with such quantum states. | ||
+ | how much randomness is present in the associated vibrational pattern. | ||
+ | in turn, has important connections with the distribution of the prime numbers. | ||
+ | |||
+ | In order to obtain these results, it was not uncommon that Riemann needed to | ||
+ | run in dedicated mode (i.e., uninterruptedly) for one week or more. | ||
+ | |||
+ | In addition to Hejhal, researchers involved in this work included Helen | ||
+ | Avelin, Fredrik Stromberg, Andreas Strombergsson, | ||
+ | |||
+ | |||
+ | |||
+ | 5/31/2012 | ||
+ | </ | ||
- | **Kontaktperson(er): |
projekt/rudel/grovinventering/riemann.1604674796.txt.gz · Last modified: 2020/11/06 15:59 by pontus