Adaptive l 1 – l 2 curve fitting

In References 1 and 2, algorithms were introduced for adaptively computing smooth piecewise polynomial approximations using uniform, least‐squars ( l 2 ) and restricted‐range uniform approximations. This present paper introduces a FORTRAN program for computing smooth piecewise polynomial approximations to data and/or precise mathematical functions (in discrete form) which allows the user the option of using best l 1 of best l 2 approximations. (The l 2 option of this newly developed l 1 – l 2 adaptive curve‐fitting package supersedes the code listed in Reference 1 for the old least‐squares program.) In this paper, adaptive curve‐fitting algorithm used in this l 1 – l 2 package is described in detail, the FORTRAN program is the given (in the Appendix) and discussed, the numerical results are presented in an effort to illustrate how the l 1 and l 2 versions of this algorithm may be used most effectively.