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Constraint addition term (Read 1390 times)

Nathan Clark

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Constraint addition term
Aug 11^th, 2006 at 1:42pm

Hello,
I am working on testing a relationship between rates and want to add an addition term to a constraint.

For example, a simple linear between 1 & 2:
rate1 := slope_parameter * rate2 + y-intercept_parameter

The slope_parameter is easy enough, but without the constant, all I can test is a relationship through the origin.
Is it possible to add such an addition term to a constraint?

Thanks for your time,
-Nathan 8)

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Sergei

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Re: Constraint addition term
Reply #1 - Aug 11^th, 2006 at 2:04pm

Dear Nathan,

You should be able to write the constraint as you have it:

Code:

rate1 := slope_parameter * rate2 + y_intercept_parameter;

If you want to use the same constraint for all branches in two trees (where each branch has a parameter 'rate' - change to whatever you actually have) you could write

Code:

global slope_parameter = 1;
global y_intercept_parameter = 0;
global y_intercept_parameter :> -1e25; /* by default all parameters must be >=0; this overrides the behavior */

ReplicateConstraint ("this1.?.rate := slope_parameter * this2.?.rate + y_intercept_parameter", tree1, tree2);

HTH,
Sergei

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Division of Infectious Diseases
Division of Biomedical Informatics
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University of California San Diego

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