Unit error, please help new user!

[shrbert724]

cai' = epsilon * (-ica - itt - kca * cai)

I get a unit error using modlunit with this equation

The previous primary expression with units: 6.02217+26 /m3-sec
is missing a conversion factor and should read:
(0.001)*()
at line 136 in file ./GPe.mod
cai' = epsilon * (-ica - itt - kca * cai)<<ERROR>>

I think this code may be helpful if anyone can figure out why there is this offset factor needed because my calculations show my equation to be correct.

UNITS {
(S) = (siemens)
(mV) = (millivolts)
(mA) = (milliamps)
(M) = (moles/liter)
(mC) = (millicoulombs)
}

epsilon = 1.0e-4 (M cm2/mC)
kca = 15.0 (mC/M s cm2)

I created mC as millicoulombs because I believe itt and ica are defaulted to mA/cm2 from this code

USEION ca READ eca WRITE ica
USEION tt READ ett WRITE itt VALENCE 2

cai is defined in M here
STATE { h n r sout siout cai (M) }


Also let me know if there is anything else i can post to make someone helping me easier or if there is a more standard format. Thank you in advance for your time.

[ted]

More information, please:

1. Why use a "magic number" (epsilon) to relate current to d conc / dt?
Even after you get your code to work, you will have a mechanism that is
very inconvenient for use with sections that have different L, diam, or nseg.
Have you examined the source code for the ion accumulation mechanisms
described in chapter 9 of The NEURON Book, or in
C:\nrn60\examples\nrniv\nmodl ?

2. Why use two different USEION statements if both currents are calcium
currents?

[shrbert724]

I fixed the unit error. We're attempting to model a system in a paper as a basis and that is how it was done. thank you for your prompt response and help!