Pierre Boulez, the former principal conductor of the New York Philharmonic who moved between conducting, composition and teaching over a long career that made him one of the leading figures in modern classical music, has died at age 90.

A spokesman for the Paris Philharmonic, Hamid Si Amer, confirmed that Boulez had died in Baden-Baden, Germany.

Even conducting extravagantly romantic music such as Wagner or Mahler, Boulez was a cool and contained presence on the podium, preferring a gray business suit and tie to tuxedo and tails, his gestures communicating logic over frenzy.

Born in Montbrison, France, Boulez initially studied mathematics as a youth before switching to music. He studied harmony at the Paris Conservatory with composer Olivier Messiaen and had lessons from Rene Leibowitz in the dissonant 20th-century style known as twelve-tone composition.

Boulez led the New York Philharmonic and the BBC Symphony Orchestra during the 1970s.

His conducting covered an enormous range, from his own compositions and those of other moderns such as Stravinsky and Stockhausen to older favorites such as Mahler, Beethoven and Bach. He also worked with the Chicago Symphony, the Cleveland Orchestra, Orchestre de Paris and the London Symphony Orchestra. His recordings won more than 25 Grammys.

As recently as 2009, already in his mid-80s, he joined with fellow conductor Daniel Barenboim to conduct the complete symphonies of Gustav Mahler at Carnegie Hall.

"Pierre Boulez made French music shine throughout the world. As a composer and conductor, he always wanted to reflect on the ages," French President Francois Hollande said in a statement.