*To*: mathgroup@smc.vnet.net*Subject*: [mg12128] Solving for coefficients...*From*: Rob Smith <rob@groucho.med.jhmi.edu>*Date*: Mon, 27 Apr 1998 01:46:12 -0400

MathGroup: I am having difficulty getting Solve[] to deal with the following problem: m = c1 A + c2 B + c3 C ... Where A, B, C etc. are known real numbers accurate to 4 decimal places and c1, c2, c3 etc. are positive integers (0 included). I can measure m to within 10 parts per million error, I would then like to solve for the coefficients. The two problems I see immediatly are 1) the coefficients can only be a positive integer or 0. To deal with this I have tried including in the body of Solve[] c1 >= 0 and IntegerQ[c1] == True. The other problem is that there is error in my measurement, I have tried to deal with this by putting the above equation into solve as two equations m >= 100.01, m <= 100.00, for example. Obviously this strategy has not worked. Any suggestions as to how to approach this problem using Mathematica would be greatly appreciated. Should any one care about the application, these are mass spectrometry data for which I am trying to solve for consistent chemical formulae. Thanks. Rob Smith Department of Biophysics & Biophysical Chemistry Johns Hopkins University School of Medicine 725 N. Wolfe St. Baltimore, MD 21205-2185 (410) 955-8712