PtrVector
gather · getval · pset · ptr_update_callback · resize · scatter · setval · size

PtrVector

class PtrVector
Syntax:
pv = new PtrVector(size)

Description:

Fast scatter and gather from a Vector to a list of pointers (must have same length). The size of the pointer vector is fixed at creation and must be an integer greater than 0. Pointers to variables are specified with the pset method. At creation, all pointers point to an internal dummy variable. So it is possible to scatter from a larger Vector into a smaller Vector.

If CVode.cache_efficient() is used, a callback should be registered with the PtrVector.ptr_update_callback() method in order to prevent memory segfaults when internal memory is reallocated.

Python Example:

from neuron import h
a = h.Vector(5).indgen()
b = h.Vector(5).fill(0)
pv = h.PtrVector(5)
for i in range(len(a)):
  pv.pset(i, b._ref_x[i])

pv.scatter(a)
b.printf()
b.mul(10)
pv.gather(a)
a.printf()

PtrVector.size()
Syntax:
length = pv.size()
Description:
Return the number of elements in the PtrVector.

PtrVector.resize()
Syntax:
newsize = pv.resize(newsize)
Description:
Old pointer array is freed and new pointer array with specified size is created. All the pointers point to a dummy variable. If the specified new size is the same as the old size, the old existing array is kept. Newsize must be an integer greater than 0.

PtrVector.pset()
Syntax:
var_val = pv.pset(i, &var)
Description:
The ith pointer in the PtrVector points to var. 0 <= i < pv.size()
PtrVector.scatter()
Syntax:
0. = pv.scatter(srcvec)
Description:
The elements of the Vector argument are copied to the variables pointed to. The size of the Vector must be the same as the size of the PtrVector

PtrVector.gather()
Syntax:
0. = pv.gather(destvec)
Description:
The variable values pointed to by the PtrVector are copied into the destination Vector.

PtrVector.getval()
Syntax:
val = pv.getval(i)
Description:
Return the value pointed to by the ith pointer in the PtrVector.

PtrVector.setval()
Syntax:
val = pv.getval(i, x)
Description:
Set the variable pointed to by the ith pointer to the value of x.

PtrVector.ptr_update_callback()
Syntax:

0. = pv.ptr_update_callback("hoc_statement", [object])

0. = pv.ptr_update_callback(pythoncallback)

Description:
The statement or pythoncallback is executed whenever range variables are re-allocated in order to establish cache efficiency. (see CVode.cache_efficient()) Within the callback, the PtrVector.resize() method may be called but the PtrVector should not be destroyed.

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