The Free On-line Dictionary of Computing (30 December 2018):

MATHLAB

   Symbolic math system, MITRE, 1964.  Later version: MATHLAB 68
   (PDP-6, 1967).

   ["The Legacy of MATHLAB 68", C. Engelman, Proc 2nd Symp on
   Symbolic and Algebraic Manip, ACM (Mar 1971)].

   [Sammet 1969, p. 498].