Differences

This shows you the differences between two versions of the page.

Link to this comparison view

gnucap:user:sensitivity_command [2016/10/17 18:17]
felixs comment on implementation status
gnucap:user:sensitivity_command [2018/10/16 15:40] (current)
felixs explain more, reference current draft implementation
Line 3: Line 3:
 see "Computer Methods for Circuit Analysis and Design (Vlach and Singhal)". see "Computer Methods for Circuit Analysis and Design (Vlach and Singhal)".
  
-In gnucap it may look like this:+Essentially, an (infinitesimal) change in a parameter p can be thought as a (infinitesimal) current injected into the network. an observable can be thought as a function f of the voltage vector v. if f is linear, then, ignoring the offset, it can be written as a scalar product s=< F, v >=<F, Gi>=<G^t^-1 F, i> with some vector F. but then df/dp=<G^t^-1 F, di/dp> 
 + 
 +now fix an observable, compute G^t^-1 F (use BSMATRIX::fbsubt), then visit the components that depend on a parameter, get the injected current and evaluate the scalar product. the result is the sensitivity of the observable wrt the parameter... 
 + 
 +In gnucap spice mode it may look like this:
  
   include netlist.ckt   include netlist.ckt
Line 18: Line 22:
 devices need to provide a ''XPROBE sens_probe_ext(string) const'' for this to work. this function uses the adjacent values from ''sim->_sens''. devices need to provide a ''XPROBE sens_probe_ext(string) const'' for this to work. this function uses the adjacent values from ''sim->_sens''.
  
-there's a "sens" command in gnucap-ufwhere the component interface and sim_data has been augmented. needs more thought before inclusion.+there's a "sens" command in gnucap-simhttp://git.savannah.gnu.org/cgit/gnucap/gnucap-plugins.git/log/?h=sim. it uses ad hoc modified components exploring the usefulness of the probe rework. needs more thought before porting upstream. 
 + 
 + - need new probe semantics, but output rework is not ready yet 
 + - parameter sensitivities (derivatives for expressions are not implemented) 
 + - need "parameter probes" to maintain spice command semantics.
gnucap/user/sensitivity_command.txt · Last modified: 2018/10/16 15:40 by felixs
 
Recent changes RSS feed Donate Powered by PHP Valid XHTML 1.0 Valid CSS Run by Debian Driven by DokuWiki