By the death of Professor Robert Rankin the University of Glasgow has lost one of its finest scholars and the mathematical community in this country one of its most highly respected members.
Robert Alexander Rankin was born in Garlieston, Wigtonshire, where his father, the Rev Oliver S Rankin, was parish minister before he became Professor of Old Testament Language, Literature and Theology in the University of Edinburgh in 1937.
Robert was educated at Garlieston School, at Fettes College in Edinburgh and at Clare College, Cambridge, which he entered with a scholarship in 1934. While studying for Part III of the Mathematical Tripos he was greatly stimulated by the lectures of JE Littlewood and AE lngham and was initiated into the kind of mathematics which became his main life's work.
After graduating BA in 1937 he began as a research student under Ingham and some work that he did on the difference between two successive prime numbers gained him a Rayleigh prize in 1939.
In the same year, Robert started under GH Hardy to elucidate some results of Ramanujan, an Indian mathematical genius, who had had no formal training in higher mathematics. When the Second World War began, Robert, like many of his contemporaries, was drafted into the Scientific Civil Service, where he worked on rockets, firstly at Fort Halstead in Kent and then in Wales, until the end of the war. He was released from war service in 1945 on condition that he would write up an account of his work on rockets. This was published in the Philosophical Transactions of the Royal Society, the paper being the longest one so far published in that journal.
After returning to Cambridge in 1945, he lectured until 1951, having been a Fellow of Clare College since 1939.
In 1951, he moved to Birmingham as Mason Professor of Pure Mathematics and remained there until 1954, when he was enticed to accept the Chair of Mathematics in the University of Glasgow by Sir Hector Hetherington, principal of the university at the time. Thus began a period of 28 years during which Robert's powerful intellect, exceptionally accurate memory and tremendous energy, along with his absolute integrity and unstinted devotion to duty, enabled him to render signal service to the university. After his retirement in 1982, he carried on as an Honorary Senior Research Fellow.
In running his department, Robert thought out everything with meticulous care and consulted others before making important decisions. He gave much thought to staff matters and always tried to be fair. He appreciated both good teaching and good research. He himself wrote one substantial textbook, An Introduction to Mathematical Analysis, at undergraduate level, while at postgraduate level he wrote two books and edited a third on modular forms. He was also joint author of a book on some work of Ramanujan. His research papers, the 100th of which he completed only recently, were mainly on the theory of numbers and on the theory of functions. Everything that he wrote was characterised by impeccable logic and absolute precision of thought.
His administrative skills were put to good use when he served as Clerk of Senate from 1971 until 1978. He regulated the affairs of that body with the utmost care and precision.
The Royal Society of Edinburgh, of which Robert was elected a Fellow in 1955 and of which he was a vice-president for a term of three years, awarded him its Keith Prize for the period 1961-1963. Although he never said so, it must have been a great disappointment to him that he was never elected a Fellow of the Royal Society. It certainly was to his colleagues, who felt that he had somehow missed out on various honours that might have been expected to come his way. However, it gave him great pleasure when the London Mathematical Society awarded him the De Morgan Medal, its most prestigious award, in 1998. He had already received the society's Senior Whitehead Prize in 1987.
Robert's main outside interests were Gaelic, music and hill-walking. He acquired his life-long interest in Gaelic while at Fettes, where George Campbell Hay, later to become a well-known Gaelic poet, was a contemporary and stimulated him greatly. Robert became a proper Gaelic scholar, not just an enthusiast. His scholarship is evident in a definitive paper on the long poem Oran na comhachag, which was published in the Transactions of the Gaelic Society of Glasgow in 1948. In this extensive paper he considered in detail the various versions of the poem and the different accounts of its history. He followed this up by a later paper on the place-names mentioned in the poem.
In 1948, he published a paper on a problem in number theory in the Proceedings of the Royal Irish Academy and written in Scottish Gaelic. He gave his name as Rob Alasdair MacFhraing, but the editors of Mathematical Reviews, not recognising it as Robert's, sent him his own paper to review! A Celtic scholar told me that the Gaelic was faultless, although obviously not written by a native speaker. Robert's detailed knowledge of Gaelic grammar showed itself also when he was an external examiner at University College, Galway, where certain mathematical papers were taken in Irish Gaelic. Much to the astonishment of his Irish colleagues, Robert pointed out a grammatical error in the wording of the rubric on one of the papers! It gave him great pleasure when he was elected honorary president of the Gaelic Society of Glasgow in 1969.
He had considerable musical talent. The organ works of JS Bach were of special interest to him and he had a detailed knowledge of many of the chorale preludes. He played the organ very competently.
On the personal side, Robert was, particularly in his younger days, rather reserved, and close friendships took time to develop. However, all who came to know him well valued his sound judgment, his transparent honesty and the absolute sincerity of his friendship. An indomitable spirit possessed by Robert was evident to all his friends during his last illness when they could not but marvel at how he battled against ever increasing weakness.
In 1942, he married Mary Ferrier Llewellyn, a close relative of the famous singer Kathleen Ferrier. The marriage, a particularly happy one, lasted until Mary's very sudden death in June 1996. Robert and she both played a prominent part in the life of the university. They had a host of friends to whom their hospitality was both generous and gracious; and their hospitality to visiting mathematicians was proverbial. They are survived by one son and three daughters.
(Byline: DAN MARTIN)
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