Wolfram Mathematica

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halirutan

00:11

@MichaelHale That's nice!

9 hours later…

becko

09:14

quick question.

How do I open multiple sessions of Mathematica in Mac?

UnchartedWorks

09:49

@becko mathematica.stackexchange.com/questions/66957/…

4 hours later…

Edmund

14:04

Is it possible to set the precision of a function? Like an attribute or someting? That is make all of the calculations in a function use a certain precision. I would like this to be 2 $MachinePrecision for a function I have defined that takes multiple variables.

JasonB

14:23

@Edmund - would something like myfunc[args__] := Block[ {$MinPrecision = 2 $MachinePrecision}, func ] work?

Michael E2

15:14

@Edmund Might want to set $MaxPrecision, too, since normally the precision of a result can be higher or lower than the inputs.

Examples: mathematica.stackexchange.com/…, for instance,

A: A problem about fixed point iteration theory

A nice trick to force Mathematica to use a given precision is to use Block and make $MinPrecision equal to $MaxPrecision. So you can write your result1 as: Block[{$MinPrecision = 10, $MaxPrecision = 10}, FixedPointList[N[1/2 Sqrt[10 - #^3] &, 10], 1.5`10]] {1.500000000, 1.286953768,...

Edmund

@JasonB That does not work. I still get MachinePrecision output.

@MichaelE2 Setting both min and max does not seem to do the trick either.

I will post a question.

Michael E2

15:49

@Edmund You have to avoid MachinePrecision numbers in your calculation. The precision tracking controlled by $MinPrecision/$MaxPrecision applies only to arbitrary precision numbers (not to machine precision or infinite precision), I think. A machine precision component "demotes" the whole calculation to machine precision.

Edmund

16:47

@MichaelE2 Humm. Just posted a question on this

Q: How to set the Precision for a function?

From this answer (19542) to my question I need to add the WorkingPrecision option to RandomVariate for that particular ProbabilityDistribution not to experience what I guess is an overflow off some sort and return incorrect values. Another option given by WRI was to use Rationalize[ #, 0]& on ea...