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Ions
====
.. hoc:function:: ion_style
Syntax:
``oldstyle = ion_style("name_ion", c_style, e_style, einit, eadvance, cinit)``
``oldstyle = ion_style("name_ion")``
Description:
In the currently accessed section,
force the named ion (eg. na_ion, k_ion, ca_ion, etc) to handle
reversal potential and concentrations according to the indicated
styles.
You will not often need this function since the
style chosen automatically on a per section basis should be
appropriate to the set of mechanisms inserted in each section.
Warning: if other mechanisms are inserted subsequent to a call
of this function, the style will be "promoted" according to
the rules associated with adding the used ions to the style
previously in effect.
The oldstyle value is previous internal setting of
c_style + 4*cinit + 8*e_style + 32*einit + 64*eadvance.
c_style: 0, 1, 2, 3.
Concentrations respectively treated as UNUSED,
PARAMETER, ASSIGNED, or STATE variables. Determines which panel (if
any) will show the concentrations.
e_style: 0, 1, 2, 3.
Reversal potential respectively treated as
UNUSED, PARAMETER, ASSIGNED, or STATE variable.
einit: 0 or 1.
If 1 then reversal potential computed by Nernst equation
on call to ``finitialize()`` using values of concentrations.
eadvance: 0 or 1.
If 1 then reversal potential computed every call to
``fadvance()`` using the values of the concentrations.
cinit: 0 or 1.
If 1 then a call to finitialize() sets the concentrations
to the values of the global initial concentrations. eg. ``nai`` set to
``nai0_na_ion`` and ``nao`` set to ``nao0_na_ion``.
The automatic style is chosen based on how the set of mechanisms that
have been inserted in a section use the ion. Note that the precedence is
WRITE > READ > unused in the USEION statement; so if one mechanism
READ's cai/cao and another mechanism WRITE's them then WRITE takes precedence
in the following table. For compactness, the table assumes the ca ion.
Each table entry identifies the equivalent parameters to the ion_style
function.
========== ========= ========= =========
cai/cao -> unused read write
========== ========= ========= =========
eca unused 0,0,0,0,0 1,0,0,0,0 3,0,0,0,1
eca read 0,1,0,0,0 1,2,1,0,0 3,2,1,1,1
eca write 0,2,0,0,0 1,2,0,0,0 3,2,0,0,1
========== ========= ========= =========
For example suppose one has inserted a mechanism that READ's eca,
a mechanism that READ's cai, cao and a mechanism that WRITE's cai, cao
Then, since WRITE takes precedence over READ in the above table,
``cai/cao`` would appear in the STATE variable panel (first arg is 3),
``eca`` would appear in the ASSIGNED variable panel (second arg is 2),
``eca`` would be calculated on a call to finitialize (third arg is 1),
``eca`` would be calculated on every call to fadvance (fourth arg is 1),
``cai/cao`` would be initialized (on finitialize) to the global variables
``cai0_ca_ion`` and ``cao0_ca_ion`` respectively. (note that this takes place just
before the calculation of ``eca``).
----
.. hoc:function:: ion_register
Syntax:
``type = ion_register("name", charge)``
Description:
Create a new ion type with mechanism name, "name_ion", and associated
variables: iname, nameo, namei, ename, diname_dv.
If any of these names already
exists and name_ion is not already an ion, the function returns -1,
otherwise it returns the mechanism type index. If name_ion is already
an ion the charge is ignored but the type index is returned.
----
.. hoc:function:: ion_charge
Syntax:
``charge = ion_charge("name_ion")``
Description:
Return the charge for the indicated ion mechanism. An error message is
printed if name_ion is not an ion mechanism.
|
