eldo_user

Post-Processing Library
Macro-Like Usage of User Defined Functions
Macro-Like Usage of User Defined Functions
An example is provided to demonstrate how two resistors obtain their values directly from a
UDF function or through a parameter (the files are realvalue.cir and realvalue.tcl). This
example demonstrates the use of a simple Tcl function returning a real value.
File realvalue.tcl listing:
proc GETVALUE { rname rval } {
# Use native Tcl syntax for expression calculation
set newvalue [expr 2*$rval + log($rval)]
}
puts "The value of resistor $rname is $newvalue"
return $newvalue
Note
The name of the function must be in uppercase in this example otherwise Eldo will not be
able to identify it, because it is not called from a .CALL_TCL command.
File realvalue.cir listing:
* Simple Tcl function returning a real value
.use_tcl realvalue.tcl
.param p1={GETVALUE("R1",TEMPER)}
.param p2=1
v1 1 0 sin(0 2 1g)
r1 1 2 p1
r2 2 0 {GETVALUE("R2",p2)}
.tran 1n 10n
.plot tran i(r1)
.end
Except for the dump of the value, the Tcl function GETVALUE is equivalent to:
.defmac GETVALUE(val) = 2*val+log(val)
UDF parameters can be real values, strings, waves, macros, UDF or keywords (see “Keyword
Parameters” on page 1142). It is important to note that for this kind of use, the UDF may be
called for each timestep. Thus wave parameters are not passed to the UDF as objects but as real
values.
The example files samphold.cir and samphold.tcl contain another example of UDF. The
function uses a Tcl namespace to keep the previous value of a wave, and is called inside a
.DEFWAVE to create a sampled representation of the input wave.
Eldo® User's Manual, 15.3 1141