On ubuntu maverick, with sbcl-1.40 I met as follows, running tests in rtest16: ********************** Problem 383 *************** Input: block([numer : true], is(abs(zeta(%i + 3) - (1.10721440843141 - .1482908671781754 %i)) < 1.e-15)) Result: false This differed from the expected result: true best regards Valery