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gatlas11-Garnet
11-Garnet
January 9, 2020
Solved

Anyway to use the Mathcad minerr function with a recursive equation?

  • January 9, 2020
  • 4 replies
  • 2726 views

Team,

 

I'm trying to use the Mathcad minerr function with a recursive equation. Ideally, the terms, r, tau, alpha, and K would be found, using initial "guess" values, Kindly see the attached sheet. 

 

Thanks,

Glen Atlas, MD, MSc

 

Best answer by AlanStevens

Mathcad doesn't do very well if you try to best fit five unknowns all in one go in this situation, so I've done the tau fit separately.  See attached.

 

Alan

 

4 replies

A
AlanStevens19-Tanzanite
19-Tanzanite
January 10, 2020

Something like the attached perhaps?  (Note the results are very sensitive to the initial guess for K).

 

Alan

 

    G
    gatlas11-GarnetAuthor
    11-Garnet
    January 10, 2020

    Dr. Stevens,

     

    This is almost what I was looking for.

     

    Note that tau represents a delay and that Mathcad would "find" the optimum delay. The purpose of this research is to investigate the oscillatory behavior of intravenous (IV) albumin in humans using a delay differential equation which is based upon the Hutchinson equation. 

     

    I appreciate your help with this tremendously. I invite you to be a co-author on this paper once it is completed.

     

    Sincerely,

    Glen Atlas, MD, MSc

    Professor
    Dept. of Anesthesiology
    Rutgers New Jersey Medical School
    Newark, NJ
    and
    Adjunct Clinical Professor
    Dept. of Biomedical Engineering
    Stevens Institute of Technology
    Hoboken, NJ

    A
    AlanStevens19-TanzaniteAnswer
    19-Tanzanite
    January 10, 2020

    Mathcad doesn't do very well if you try to best fit five unknowns all in one go in this situation, so I've done the tau fit separately.  See attached.

     

    Alan

     

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