Vietnam News, Sunday, 19 November 2006.
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(19-11-2006)
Dang Dinh Ang is more than a mathematician and engineer; he’s also a teacher determined to make math fun for his students. In honour of National Teachers’ Day tomorrow, Hong Van spends a day in the busy life of Ang.
Google the name Dang Dinh Ang and the search engine results bring up 24 pages of professional websites that include the titles of his many articles published in mathematics journals.
The most cited work of Prof Ang’s is his textbook Moment Theory and Some Inverse Problems in Potential Theory and Heat Conduction, co-authored by Ang, when he was 76 years old, and two other mathematicians, one Vietnamese and the other German.
Ang’s research results are used in the fields of mechanical and aeronautical engineering.
The textbook, published by the prestigious German Springer publishing house, is widely used at universities in the US, Germany, France, Belgium and Japan as a textbook or must-read for post-graduates and undergraduates.
To the general Vietnamese public, Prof might not be well-known, but to mathematicians and engineering professionals he is a highly respected figure.
"Prof Ang has contributed almost 50 years to the Vietnamese mathematics field," said Prof Nguyen Xuan Xanh, Ang’s former student. "He is well-known through more than 130 articles published in international mathematics journals, magazines and books."
Born in northern Ha Tay Province’s Chuong My District, Ang moved to Sai Gon in 1951 with his wife.
Fluent in French after his school years at the prestigious Buoi High School in Ha Noi, Ang decided to study English by himself so he could earn a living as an English language teacher.
In 1953, he won a Fulbright scholarship funded by the US government and later studied aeronautical engineering at the University of Kansas.
During a talk show with HCM City TV in March on his 80th birthday, Ang modestly said he had always been lucky in his career, but his former students in the audience said he had worked hard and contributed a great deal to Viet Nam.
Instead of the standard four years for a bachelor’s degree, Ang finished within two years, and wrapped up his two-year master’s programme in one year.
After that, he spent two years earning a Ph.D in aeronautics and mathematics at California Institute of Technology (Caltech).
As early as 1955, prior to getting his bachelor’s degree, Ang won a prize from the Institute of Aeronautical Sciences in Fort Worth, Texas, for his paper on compressible viscous flow in the field of aviation engineering.
At that time, he had many offers to stay in the US to continue his professional career.
In 1960, he decided to return to southern Viet Nam, then under a US-supported government, to his wife and two children who could not go to the US because of the then existing regulations.
After Ang returned at the age of 34, he was assigned as the head of the mathematics department of then Sai Gon University, now the Viet Nam National University – HCM City.
New way of teaching
"At that time the old system made maths one of the toughest subjects to take," Ang recalled. "The programme scared the students with challenges that shouldn’t exist."
Duong Minh Duc, also a former student who is now a professor at the HCM City National University’s School of Natural Sciences, said that before he went to university in the early 1970s, only 12 of 500 students taking the general maths courses could pass the exams after the first two undergraduate years.
"Two years after Prof Ang changed the system and the programme, the number of graduates increased to nearly 100," Duc said, "but the important thing is that he inspired us to like mathematics."
Duc also said the studies had been so arduous that only a handful of people graduated with a maths degree during the decade prior to Ang taking over the programme.
"What we learned from Prof Ang is still useful for us as educators," Duc said. "He showed us that teaching is not about hindering, but about inspiring students and making studying math fun for people who like it."
For many university mathematics lecturers, Ang’s textbooks about maths and mechanics that he wrote years ago are still relevant and used widely.
In 1980, to recognise his academic contributions, Ang was among the first group of academia in Viet Nam to be given the title of professor from the Government.
He has also been a visiting professor and lecturer at many well-known universities in the world, including the University of California Los Angeles and the University of Utah in the US.
He has lectured at the University of Cambridge in England, Instituto per le Applicasioni del Calcolo Mauro Picone in Rome, Universite D’Orleans in France, Universite Paris – Nord, Ecole Polytechnique Paris, Free University in Berlin, and University of Tokyo.
To celebrate his 80th birthday in March, the Paris Ecole Polytechnique and the HCM City Institute of Applied Mechanics are co-organising an international conference on nonlinear analysis and engineering mechanics in HCM City next month.
The workshop is expected to bring to Viet Nam many leading mathematicians from the US, Germany, France, China, Canada, Japan, Australia, Germany and Hong Kong.
Fluting mathematician
Leaving behind the busy traffic noise on HCM City’s Dien Bien Phu Street, Ang separates himself by bamboo trees, ornamental plants and a small fishpond.
He lives in a simple house with a set of old rattan chairs, a rattan sofa and coffee table, some old bookshelves filled with books, a small Sony television, a Vietnamese-made DVD player and an old piano.
The walls are covered with copies of his degrees, pictures of him and other colleagues, and posters for flute festivals he has taken part.
Well-known for his mathematics knowledge, Ang is also popular in his field as a flutist.
He said he didn’t know why he liked the instrument so much, but he loved playing a bamboo flute when he was little. The first time he heard Mozart, he fell in love with classical music.
Perhaps the talent runs in the family. His nephew, Dang Thai Son was the first Asian pianist to win first prize and a gold medal at the 10th International Chopin Piano Competition prize in Warsaw in 1980.
Soon after Ang arrived in the US, he bought a silver flute, which has been with him ever since.
For Ang, music is important to his mathematics career, and he finds the two complementary.
Music is also invigorating, he said, and he especially likes Mozart, Haydn, and the late Vietnamese composers Van Cao and Trinh Cong Son, who were his close friends.
His wife, Bui Thi Minh Thi, now 78, raised their five children. When Ang got his Ph.D, his department at CalTech issued a PHT (Put Husband Through) degree for Thi.
When it was given to her, she burst into tears, recalling all the years she was separated from her husband and her efforts to raise the two children while he was away.
Today, she remembers that it was a difficult time because her relatives often urged her to persuade him to return.
"But I thought if he was unfaithful to me, he would have been, anyway, even if we were together, so I told him to finish as soon as he could and come home," she said.
Of their five children, three are following Ang’s path in the US.
His second son has earned a Ph.D in mathematics at Princeton University in New Jersey, and a daughter and another son are teaching in Florida and Mississippi.
His fourth daughter is working in a hospital in Belgium, while his last daughter is teaching English at the Viet Nam-US Society (VUS), an English-language centre in HCM City.
These days, Prof Ang gets up every day at 4am and plays his beloved instrument for nearly an hour. He still rides his 1966 bicycle around town and is practising his flute to prepare for a CD recording early next year of works by the German baroque composer Telemann.
On the recording, he will be accompanied by two other musicians, a well-known Vietnamese flutist and pianist. — VNS
