In the vein of my fixed point alogorithm, comes another roots estimating algorithm, the ole' bisection algorithm. In the global variable, 'G', place the function of X, as in 'X:2-4' stack level -> 4: lower endpoint 3: upper endpoint 2: tolerance level (maximum error) 1: maximum number of iteration << 1 -> a b tol n0 i << WHILE i n0 <= REPEAT b a - 2 / a + 'p' STO p 'X' STO IF G EVAL 0 == b a - 2 / tol < OR THEN p { p X } PURGE ABORT END i 1 + 'i' STO IF G EVAL a 'X' STO g EVAL * 0 > THEN p 'a' STO ELSE p 'b' STO END i p b a - ABS p 'X' STO G EVAL 4 ->LIST SHON HALT DROP END 'Failed' { p X } PURGE >> >> For SHON - see my previous artical - all it does is turn on the shift key - makes life easier.... Anyways.... as always....send any questions, comments, etc. to me.... I'd love to hear from you. Happy HP-ing! ******************************************************************** * J.J. * JJL101@psuvm.bitnet * * * Penn State Center for Academic Computing * * John Lehett * Computational Mathematics * ********************************************************************