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FanCG1-Visitor
1-Visitor
August 25, 2010
Solved

Help: another question on estimating reaction rate constants with mathcad

  • August 25, 2010
  • 28 replies
  • 14661 views

Hi, everyone

i m a greenhand on mathcad, and I want to solve some of my old problems using mathcad, which have been solved by matlab and maple .

yesterday I encountered a chemical kinetics problem, which I can easily handle through matlab nonlinear toolbox. I reviewed some similar threads in our forum, and cannot apply the method (Minerr, Minimize,etc) into my worksheet.

Maybe I need some help (see the attached mathcad14 or 11 file where I describe my question)

questions2.JPG

questions.JPG

Best answer by AlanStevens

See attached, saved in M14/15 format as M11 doesn't find a solution.

You have k1 as the rate constant for "B". I've assumed this should be k2 - you'll need to change this if I'm wrong.

There is probably a slicker solution but it's a start!

Alan

NB I've edited this file as I realised the solution I posted earlier was wrong.

28 replies

jeanGiraud1-Visitor
1-Visitor
August 25, 2010

If you don't get a quick answer, "save as" Mathcad version 11or lower

Just the data set, nothing else.

jmG

AlanStevens19-TanzaniteAnswer
19-Tanzanite
August 25, 2010

See attached, saved in M14/15 format as M11 doesn't find a solution.

You have k1 as the rate constant for "B". I've assumed this should be k2 - you'll need to change this if I'm wrong.

There is probably a slicker solution but it's a start!

Alan

NB I've edited this file as I realised the solution I posted earlier was wrong.

jeanGiraud1-Visitor
1-Visitor
August 25, 2010

>See attached, ......... as M11 doesn't find a solution.<

_______________________

It does for me !

MCADfit_4.gif

jmG

jeanGiraud1-Visitor
1-Visitor
August 26, 2010

>I've just downloaded the M11 converted format Viktor files and tested them in M11. I don't see the behaviour you report. They run ok in M11 (though they are just short of 15 times slower than in M14) and do not cause my computer or even Mathcad to crash. Did you just run them once, or did the crash happen after you modified something or what ?<

PTC Mathcad versions are just not Mathcad [piece of scrap]. If it runs, that's one thing. If it crashes Mathcad, eventually the all box, or other kind of error , it results from the impossibility to to do anything significant in the converted work sheet. My observations are not casual and only pertaining to this particular transmission, no: my observations are anterior to a very recent from [ ...] that PTC had no other interest in Mathcad than their version 15 [which I call version sub-zero] ... This compobox does not even print on the screen as fast as I type 2 fingers, what would it be with 10 fingers !!!

All that to say : thanks for this wonderful project, all done in < 5 minutes "Glorious Mathcad 11". Calculation time < 5 seconds as long as the initials will initialize. How many seconds in your 14 ? Your DE system is as expected not correctly dressed.

MCADodesolve_1.gif

Not sure what ERR means in that case ???

Jean

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