Set of numbers in Mma 3.0 is smaller tha

*To*: mathgroup at smc.vnet.net*Subject*: [mg7555] Set of numbers in Mma 3.0 is smaller tha*From*: Ersek_Ted%PAX1A at mr.nawcad.navy.mil*Date*: Fri, 13 Jun 1997 19:38:06 -0400 (EDT)*Sender*: owner-wri-mathgroup at wolfram.com

I noticed that Mma 3.0 has two new system variables $MaxNumber, and $MinNumber. Suppose you need to work with numbers larger than $MaxNumber. or closer to zero than $MinNumber. All you have to do is change the value of $MaxNumber or $MinNumber. Sounds easy right ? Well I tired, and couldn't. Do I need to work with really big numbers or really tiny numbers? No. I was just exploring the limitations of the system. However, I wonder if some users that are affected by this apparent limitation. I will point out that you can work with numbers that exceed the limitations imposed by $MinNumber and $MaxNumber as long as the kernal doesn't try to compute the numerical value. For example you will have no trouble working with Exp[10^15] even though it exceeds $MaxNumber. Just don't try to do N[Exp[10^15]]. Now does it take an awful long time to do calculations with very big numbers? Sometimes it does. Consider the lines below: In[1]:= a=$MaxNumber; x1=Sqrt[a] 0.8; x2=Sqrt[a] 0.85; In[2]:= (* My 90 Mhz Pentium computes the following in a flash *) x1 x2; In[2]:= (* However it takes about 5 minutes to find the half billion digits in the following *) (* Even though I followed it with a semi-colon. *) Floor[a]; As I would expect it seems it is practical to work with huge numbers as long as the amount of Precision needed isn't huge. I don't see why a user should be prohibited from doing similar calculations with numbers that are much much larger than $MaxNumber. It seems to me Version 2.2 had no such limitation built in. I thought you were only limited by the storage capacity of your computer, and the time you were willing to wait. Questions: - Are there any applications that need to go outside the above limitations ? - Can a user increase $MaxNumber, or decrease the magnitude of $MinNumber ? - Does Version 2.2 give good results when the values are outside the above limitations ? - Did WRI impose a limitation on the range of numerical values so that the program could run faster? Ted Ersek ersek_ted%pax1a at mr.nawcad.navy.mil

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