
Computer Science Computer Science Forum 
 LinkBack  Thread Tools  Display Modes 
August 31st, 2010, 08:49 AM  #1 
Newbie Joined: Aug 2010 Posts: 3 Thanks: 0  Logarithms and Reversing them
Not sure if this is the right area.... been out of math for awhile. Log10(P) =( A  (B / T)  (C * Log10(T)) + (D * T) + (( E * (F  T)) / F * T) * Log10(F  T)) Formula for r22 temperature to pressure conversion Where if T = 50 then P = 85 (rounded) Now I am trying to reverse it to Get T from P, according to Antoine Equation for pressure temperature relations T = (B / (A  Log10(P)))  C But I can't figure out the rest of the reverse equation to get the Temperature from the Pressure A = 29.35754453 B = 3845.1931152 C = 7.86103122 D = 0.002190939044 E = 305.8268131 F = 686.1 This are the Fixed Coefficients for the Whole Calculations if anyone needs them... Thanks, C.W. 
August 31st, 2010, 11:24 AM  #2 
Global Moderator Joined: Nov 2006 From: UTC 5 Posts: 16,046 Thanks: 938 Math Focus: Number theory, computational mathematics, combinatorics, FOM, symbolic logic, TCS, algorithms  Re: Logarithms and Reversing them
There isn't going to be any nice inverse formula. I'm not even sure if you could solve it explicitly with Lambert's W. The best way would be with a numerical method like the secant method or Brent's method.

August 31st, 2010, 08:59 PM  #3 
Global Moderator Joined: Dec 2006 Posts: 20,833 Thanks: 2161 
Problem already posted and replied to here: viewtopic.php?f=13&t=15557 so topic locked. 

Tags 
logarithms, reversing 
Thread Tools  
Display Modes  

Similar Threads  
Thread  Thread Starter  Forum  Replies  Last Post 
Help reversing an algorithm...  Vidofner  Applied Math  4  January 12th, 2014 08:47 AM 
Help reversing formula  oneup  Elementary Math  4  September 2nd, 2013 04:08 AM 
Reversing the order of Integration  OSearcy4  Calculus  4  October 17th, 2009 03:32 PM 
Reversing the order of integration  Gotovina7  Calculus  1  February 29th, 2008 09:30 AM 
Reversing Digits  Cat  Number Theory  6  January 7th, 2007 07:32 PM 