Floating point error

Phoenix Certara Forums Modelling and Simulation
1

Hi!

I have an issue with my Phoenix Winnonlin ASCII model. Here’s my differential equations:

DZ(1)= -KA*Z(1)

DZ(2)=KAZ(2) - KELZ(2)

DZ(3)=Constant ( 1 - ( 0.954 * IC50**Hill / ( (Z(2)/Vfu)Hill + IC50Hill ) ) ) - Constant*Z(3)

I get error message “Processing halted due to floating point error: INVALID NUMBER” when I use this hill parameter (temporary variable) and rational numbers such as 0.7 , 2.3 etc. There’s also same error message when using simulation mode. Already I have resolved that simulation and parameter estimating work if I use whole number 0,1,2,3,4…

I have also other differential equations with exponent (used decimal numbers) but these work properly.

best regards

MH

2

Hi ? Johanna,

I’m not sure I can answer your question without seeing your data or at least some subset of it, maybe parametising with dose and conc values standardised to a common unit would help e.g. if conc was ug/mL and dose was 10 mg then enter 10000ug.

Also the WNL classic engine is old and particularly for custom models I think you will have more success with PML in the Phoenix model engine, have yout tried your model in that?

Simon.