*To*: mathgroup@smc.vnet.net*Subject*: [mg11945] Numeric Accuracy*From*: hello@there.com (Rod Pinna)*Date*: Thu, 9 Apr 1998 00:33:35 -0400*Organization*: UWA

Hello all, I have a problem which is confusing me a bit. I have a rather long calculation, the results of which I am comparing to a finite element solution. Now, in defining the problem, I have a set of physical dimensions. For the sake of discussion, they are a=10, t=0.05, L=16.1886, W=207x10^9, n=0.3. Leaving these as is, my analytic solution gives two solutions, 395325 and 128095. There is also a "wave number" (an integer) associated with these. The second of these solutions is correct within 3%, and predicts the same wave number as the FE solution. However, when enter the dimensions as follows: a=10,t=0.05`1000,L=16.1886`1000,W=207x10^9,n=0.3`1000 The solution now produces two solutions which are almost exactly the same, and have a value about 310551.7, which is quite a long way from the correct solution. So, my question is, should I trust the machine precision solution, on the arbitrary precision solution? Rod Pinna (rpinnaX@XcivilX.uwa.edu.au Remove the X for email)