You can't exactly say that Dane Rudhyar is an unknown or misunderstood genius--like Charles Ives, for example. Samples of his work have been available on records through most of the LP era, with nearly a dozen pieces currently listed in the Schwann Catalog. His music was first performed in this country--by Pierre Monteux, no less--in 1917, not long after he arrived here from his native France. And his writings (mostly on astrology) are familiar to thousands of Americans. Still, when the Kennedy Center announced its imaginative "American Portraits" series, honoring six composers who range from Aaron Copland to Philip Glass, Rudhyar's was the odd name out. Dane who? An astrologer?

Last night's concert in the Terrace Theater documented Rudhyar's right to such recognition, though he might easily have missed it. For years, he told his audience, he could not "find people to perform my music," and so he stopped composing and turned to astrology, where his efforts were well rewarded. Now, nearing his 87th birthday, he has lived into a time when his work no longer seems "strange." At this point, it is easy to see a strong personality in and behind the music.

The pre-1920 pieces performed last night (three "Poe mes Tragiques" for mezzo-soprano, violin and piano; three Melodies for flute, cello and piano) have a period charm but not much originality--good work for a young composer who was largely self-taught. But his Five Stanzas for String Orchestra (1925-26), brilliantly interpreted by Paul Zukofsky and the Colonial Symphony, are concise, powerful music--strongly felt, well-conceived for the performing medium and technically innovative for their time. This sounded like a very challenging score, but the orchestra took it skillfully in stride.

His most recent work, the Epic Poem for piano (1979) is equally impressive--rich in germinal melodies which took on a strange beauty and power in Robert Black's expert performance.