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The cumulative form of the Cumulative Weibull equation with intercepts is immediately below:
y=a+b(1-exp(-((x+dln(2)1/e-c)/d)e))
I have tried to get it to run in WinNonlin as a user model as follows:
remark equation y=a+b(1-exp(-((x+dln(2)**1/e-c)/d)**e))
F is percent dissolved and X is time. b is intercept on y axis, and e is the intercept on the x axis.
remark - define model-specific commands COMMANDS NPARAMETERS 5 PNAMES "a", "c", "b", "d", "e"
END
FUNC 1
expon = -((x+dln(2)**1/e-c)/d)**e)
F = a+b(1-exp(expon)
END
EOM
With an x, y data set file in place the program did not run. Please can I be advised as to the code which will run?
Angus McLean
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The following message was posted to: PharmPK
Angus,
What exactly is the error message you are seeing? It could be an issue to do with your initial estimates for instance; if you log this with support.-at-.pharsight.com they can point you to possible options to resolve the problem.
You may also seek out tips and discuss Pharsight products with other users at ww.pharsight.com/extranet (free access but a login is required)
Lastly to assist with users upgrade planning please be aware that Phoenix WinNonlin 6.2 will be due at the end of the year and will support the IVIVC tool kit, AutoPilot as well as some minor general fixes and NLME enhancements. (That said a 'typical' NCA user should be fine with 6.1).
Best regards,
Simon.
--
Simon.Davis.aaa.certara.com
Senior Scientific Consultant
Pharsight- A Certara(tm) Company
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Tuesday October 12, 2010:
Simon: the error message I get is INVALID STATEMENT at the line beginning
expon
It may be a question of how the equation is written in the code.
I repeat as previous see below.
The cumulative form of the Cumulative Weibull equation with intercepts is immediately below:
y=a+b(1-exp(-((x+dln(2)1/e-c)/d)e))
I have tried to get it to run in WinNonlin as a user model as follows:
remark equation y=a+b(1-exp(-((x+dln(2)**1/e-c)/d)**e))
F is percent dissolved and X is time. b is intercept on y axis, and e is the intercept on the x axis.
remark - define model-specific commands COMMANDS NPARAMETERS 5 PNAMES "a", "c", "b", "d", "e"
END
FUNC 1
expon = -((x+dln(2)**1/e-c)/d)**e)
[How about
expon = -((x + (d * ln(2)**(1/e)) - c)/d)**e)
The dln at least should be d*ln - db]
F = a+b(1-exp(expon)
END
EOM
With an x, y data set file in place the program did not run. Please can I be advised as to the code which will run?
Angus McLean
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Natural log in Winnonlin is implemented as DLOG( ) or LOGE( ). There were also some unmatched parantheses in the code. If I understand your equation correctly, then its implementation should be something like:
FUNCTION 1
expon = -(((x+d*DLOG(2)**1/e-c)/d)**e) F = a+b*(1-exp(expon))
END
EOM
In past, I used the following form of Weibull
c = lag time
d=shape factor
e=constant
FUNCTION 1
Tdiff=x-c
if Tdiff>0 then
expon=-((Tdiff)**d)/e
else
expon=0
endif
F = a+b*(1-exp(expon))
END
EOM
Hope this helps
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