Re: The development of powder profile refinement...
On 08/10/2018 10:55 AM, Alan Hewat wrote: Thanks Henk (and Bob). It's a story that must be quite common in science. Humans like to simplify, and identify with heros. Humanity teaches us that we stand on the shoulders of others. Few discoveries, especially in science, are made by a single individual. Profile Refinement was perhaps an idea "whose time had come" with the application of computers. But the stroke of genius was to refine the structure directly from the data points, rather than first refine structure factors. Even that may have been simply because computers at that time could only handle a limited number of parameters. A fascinating story. Alan. Henk, I agree with Alan that you told a fascinating story, and not what I was expecting. It is always a temptation to give yourself more credit than an unbiased observer might allow. This case represents a most egregious instance. To show the state of early computing, one of the graduate students in Crystallography in the Geology Department at the University of Minnesota when I started in 1962, was awarded a PhD for writing a computer program to calculate powder patterns! This was on a Univac 1103 with capabilities similar to that of the computer described in Bob and Henk's article. With such limited capabilities, you had to choose the problem with considerable care. By the time I graduated 5 years later, the University had a CDC 6600 "supercomputer", which had the blazing speed of 3 megaFLOPS (double precision)! For comparison, this is roughly the performance of an x86 machine with an 0.7 GHz clock!! Larry ++ Please do NOT attach files to the whole list Send commands to eg: HELP as the subject with no body text The Rietveld_L list archive is on http://www.mail-archive.com/rietveld_l@ill.fr/ ++
Re: The development of powder profile refinement...
Thanks Henk (and Bob). It's a story that must be quite common in science. Humans like to simplify, and identify with heros. Humanity teaches us that we stand on the shoulders of others. Few discoveries, especially in science, are made by a single individual. Profile Refinement was perhaps an idea "whose time had come" with the application of computers. But the stroke of genius was to refine the structure directly from the data points, rather than first refine structure factors. Even that may have been simply because computers at that time could only handle a limited number of parameters. A fascinating story. Alan. On 9 August 2018 at 12:32, wrote: > Bob van Laar and I wrote an article about the development of the powder > Profile Refinement at the Reactor Centre Netherlands. This method is later > called Rietveld refinement. We show that there were three persons involved > in this enterprise, Bert Loopstra for the idea, Bob van Laar for the > mathematical treatment and Hugo Rietveld for the computer program, rather > than one. For all users of the method it will be interesting to read. > > The article (Acta Cryst. (2018). A74, 88-92) is Open Access and can be > downloaded from: http://journals.iucr.org/a/issues/2018/02/00/ib5058/ > ib5058.pdf > > At the moment it is the most read article of Acta Cryst. A of the last 6 > months: http://178.33.252.149/a/services/mostread.html > > Kind greetings, > Henk Schenk > __ * Dr Alan Hewat, NeutronOptics, Grenoble, FRANCE * +33.476.98.41.68 http://www.NeutronOptics.com/hewat __ ++ Please do NOT attach files to the whole list Send commands to eg: HELP as the subject with no body text The Rietveld_L list archive is on http://www.mail-archive.com/rietveld_l@ill.fr/ ++
