circuit.cpp

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/*
 * circuit.cpp - circuit class implementation
 *
 * Copyright (C) 2003, 2004, 2005, 2006, 2008 Stefan Jahn <stefan@lkcc.org>
 *
 * This is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation; either version 2, or (at your option)
 * any later version.
 * 
 * This software is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 * 
 * You should have received a copy of the GNU General Public License
 * along with this package; see the file COPYING.  If not, write to
 * the Free Software Foundation, Inc., 51 Franklin Street - Fifth Floor,
 * Boston, MA 02110-1301, USA.  
 *
 * $Id: circuit.cpp 1825 2011-03-11 20:42:14Z ela $
 *
 */

#if HAVE_CONFIG_H
# include <config.h>
#endif

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <assert.h>

#include "logging.h"
#include "complex.h"
#include "object.h"
#include "matrix.h"
#include "node.h"
#include "property.h"
#include "valuelist.h"
#include "tvector.h"
#include "history.h"
#include "circuit.h"
#include "microstrip/substrate.h"
#include "operatingpoint.h"
#include "characteristic.h"
#include "component_id.h"

// normalising impedance
const nr_double_t circuit::z0 = 50.0;

// Constructor creates an unnamed instance of the circuit class.
circuit::circuit () : object (), integrator () {
  size = 0;
  MatrixN = MatrixS = MatrixY = NULL;
  MatrixB = MatrixC = MatrixD = NULL;
  VectorQ = VectorE = VectorI = VectorV = VectorJ = NULL;
  MatrixQV = NULL;
  VectorCV = VectorGV = NULL;
  nodes = NULL;
  pacport = 0;
  pol = 1;
  flag = CIRCUIT_ORIGINAL | CIRCUIT_LINEAR;
  subst = NULL;
  vsource = -1;
  vsources = 0;
  nsources = 0;
  inserted = -1;
  subcircuit = NULL;
  subnet = NULL;
  deltas = NULL;
  histories = NULL;
  nHistories = 0;
  type = CIR_UNKNOWN;
}

/* Constructor creates an unnamed instance of the circuit class with a
   certain number of ports. */
circuit::circuit (int s) : object (), integrator () {
  assert (s >= 0);
  size = s;
  if (size > 0) nodes = new node[s];
  MatrixN = MatrixS = MatrixY = NULL;
  MatrixB = MatrixC = MatrixD = NULL;
  VectorQ = VectorE = VectorI = VectorV = VectorJ = NULL;
  MatrixQV = NULL;
  VectorCV = VectorGV = NULL;
  pacport = 0;
  pol = 1;
  flag = CIRCUIT_ORIGINAL | CIRCUIT_LINEAR;
  subst = NULL;
  vsource = -1;
  vsources = 0;
  nsources = 0;
  inserted = -1;
  subcircuit = NULL;
  subnet = NULL;
  deltas = NULL;
  histories = NULL;
  nHistories = 0;
  type = CIR_UNKNOWN;
}

/* The copy constructor creates a new instance based on the given
   circuit object. */
circuit::circuit (const circuit & c) : object (c), integrator (c) {
  size = c.size;
  pol = c.pol;
  pacport = c.pacport;
  flag = c.flag;
  type = c.type;
  subst = c.subst;
  vsource = c.vsource;
  vsources = c.vsources;
  nsources = c.nsources;
  inserted = c.inserted;
  subnet = c.subnet;
  deltas = c.deltas;
  nHistories = c.nHistories;
  histories = NULL;
  subcircuit = c.subcircuit ? strdup (c.subcircuit) : NULL;

  if (size > 0) {
    // copy each node and set its circuit to the current circuit object
    nodes = new node[size];
    for (int i = 0; i < size; i++) {
      nodes[i] = node (c.nodes[i]);;
      nodes[i].setCircuit (this);
    }
    // copy each s-parameter
    if (c.MatrixS) {
      allocMatrixS ();
      memcpy (MatrixS, c.MatrixS, size * size * sizeof (nr_complex_t));
    }
    // copy each noise-correlation parameter
    if (c.MatrixN) {
      allocMatrixN (nsources);
      int i = size + nsources;
      memcpy (MatrixN, c.MatrixN, i * i * sizeof (nr_complex_t));
    }
    // copy each HB-matrix entry
    if (c.MatrixQV) {
      allocMatrixHB ();
      memcpy (MatrixQV, c.MatrixQV, size * size * sizeof (nr_complex_t));
      memcpy (VectorGV, c.VectorGV, size * sizeof (nr_complex_t));
      memcpy (VectorCV, c.VectorCV, size * sizeof (nr_complex_t));
      memcpy (VectorQ, c.VectorQ, size * sizeof (nr_complex_t));
    }
    // copy each G-MNA matrix entry
    if (c.MatrixY) {
      allocMatrixMNA ();
      memcpy (MatrixY, c.MatrixY, size * size * sizeof (nr_complex_t));
      memcpy (VectorI, c.VectorI, size * sizeof (nr_complex_t));
      memcpy (VectorV, c.VectorV, size * sizeof (nr_complex_t));
      if (vsources > 0) {
    memcpy (MatrixB, c.MatrixB, vsources * size * sizeof (nr_complex_t));
    memcpy (MatrixC, c.MatrixC, vsources * size * sizeof (nr_complex_t));
    memcpy (MatrixD, c.MatrixD, vsources * vsources * sizeof (nr_complex_t));
    memcpy (VectorE, c.VectorE, vsources * sizeof (nr_complex_t));
    memcpy (VectorJ, c.VectorJ, vsources * sizeof (nr_complex_t));
      }
    }
  }
  else {
    nodes = NULL;
    MatrixS = MatrixN = MatrixY = NULL;
    MatrixB = MatrixC = MatrixD = NULL;
    VectorQ = VectorE = VectorI = VectorV = VectorJ = NULL;
    MatrixQV = NULL;
    VectorCV = VectorGV = NULL;
  }

  // copy operating points
  oper = valuelist<operatingpoint> (c.oper);
}

// Destructor deletes a circuit object.
circuit::~circuit () {
  if (size > 0) {
    if (MatrixS) delete[] MatrixS;
    if (MatrixN) delete[] MatrixN;
    freeMatrixMNA ();
    freeMatrixHB ();
    delete[] nodes;
  }
  if (subcircuit) free (subcircuit);
  deleteHistory ();
}

/* With this function the number of ports of the circuit object can be
   changed.  Previously stored node and matrix information gets
   completely lost except the current size equals the given size. */
void circuit::setSize (int s) {
  // nothing to do here
  if (size == s) return;
  assert (s >= 0);

  if (size > 0) {
    // destroy any matrix and node information
    if (MatrixS) delete[] MatrixS;
    if (MatrixN) delete[] MatrixN;
    MatrixS = MatrixN = NULL;
    freeMatrixMNA ();
    delete[] nodes; nodes = NULL;
  }

  if ((size = s) > 0) {
    // re-create matrix and node information space
    nodes = new node[size];
    allocMatrixS ();
    allocMatrixN (nsources);
    allocMatrixMNA ();
  }
}

/* Destroys the HB-matrix memory. */
void circuit::freeMatrixHB (void) {
  if (VectorQ) { delete[] VectorQ; VectorQ = NULL; }
  if (MatrixQV) { delete[] MatrixQV; MatrixQV = NULL; }
  if (VectorCV) { delete[] VectorCV; VectorCV = NULL; }
  if (VectorGV) { delete[] VectorGV; VectorGV = NULL; }
}

/* Allocates the HB-matrix memory. */
void circuit::allocMatrixHB (void) {
  if (VectorQ) {
    memset (VectorQ, 0, size * sizeof (nr_complex_t));
  } else {
    VectorQ = new nr_complex_t[size];
  }
  if (MatrixQV) {
    memset (MatrixQV, 0, size * size * sizeof (nr_complex_t));
  } else {
    MatrixQV = new nr_complex_t[size * size];
  }
  if (VectorCV) {
    memset (VectorCV, 0, size * sizeof (nr_complex_t));
  } else {
    VectorCV = new nr_complex_t[size];
  }
  if (VectorGV) {
    memset (VectorGV, 0, size * sizeof (nr_complex_t));
  } else {
    VectorGV = new nr_complex_t[size];
  }
}

/* Allocates the S-parameter matrix memory. */
void circuit::allocMatrixS (void) {
  if (MatrixS) {
    memset (MatrixS, 0, size * size * sizeof (nr_complex_t));
  } else {
    MatrixS = new nr_complex_t[size * size];
  }
}

/* Allocates the noise correlation matrix memory. */
void circuit::allocMatrixN (int sources) {
  nsources = sources;
  if (MatrixN) delete[] MatrixN;
  MatrixN = new nr_complex_t[(size + sources) * (size + sources)];
}

/* Allocates the matrix memory for the MNA matrices. */
void circuit::allocMatrixMNA (void) {
  freeMatrixMNA ();
  if (size > 0) {
    MatrixY = new nr_complex_t[size * size];
    VectorI = new nr_complex_t[size];
    VectorV = new nr_complex_t[size];
    if (vsources > 0) {
      MatrixB = new nr_complex_t[vsources * size];
      MatrixC = new nr_complex_t[vsources * size];
      MatrixD = new nr_complex_t[vsources * vsources];
      VectorE = new nr_complex_t[vsources];
      VectorJ = new nr_complex_t[vsources];
    }
  }
}

/* Free()'s all memory used by the MNA matrices. */
void circuit::freeMatrixMNA (void) {
  if (MatrixY) { delete[] MatrixY; MatrixY = NULL; }
  if (MatrixB) { delete[] MatrixB; MatrixB = NULL; }
  if (MatrixC) { delete[] MatrixC; MatrixC = NULL; }
  if (MatrixD) { delete[] MatrixD; MatrixD = NULL; }
  if (VectorE) { delete[] VectorE; VectorE = NULL; }
  if (VectorI) { delete[] VectorI; VectorI = NULL; }
  if (VectorV) { delete[] VectorV; VectorV = NULL; }
  if (VectorJ) { delete[] VectorJ; VectorJ = NULL; }
}

/* This function sets the name and port number of one of the circuit's
   nodes.  It also tells the appropriate node about the circuit it
   belongs to.  The optional 'intern' argument is used to mark a node
   to be for internal use only. */
void circuit::setNode (int i, const char * n, int intern) {
  nodes[i].setName (n);
  nodes[i].setCircuit (this);
  nodes[i].setPort (i);
  nodes[i].setInternal (intern);
}

// Returns one of the circuit's nodes.
node * circuit::getNode (int i) {
  return &nodes[i];
}

// Sets the subcircuit reference for the circuit object.
void circuit::setSubcircuit (char * n) {
  if (subcircuit) free (subcircuit);
  subcircuit = n ? strdup (n) : NULL;
}

#if DEBUG
// DEBUG function:  Prints the S parameters of this circuit object.
void circuit::print (void) {
  for (int i = 0; i < getSize (); i++) {
    for (int j = 0; j < getSize (); j++) {
      logprint (LOG_STATUS, "%s S%d%d(%+.3e,%+.3e) ", getName (), i, j, 
        (double) real (getS (i, j)), (double) imag (getS (i, j)));
    }
    logprint (LOG_STATUS, "\n");
  }
}
#endif /* DEBUG */

/* Returns the current substrate of the circuit object.  Used for
   microstrip components only. */
substrate * circuit::getSubstrate (void) { 
  return subst;
}

// Sets the substrate of the circuit object.
void circuit::setSubstrate (substrate * s) {
  subst = s;
}

/* Returns the circuits B-MNA matrix value of the given voltage source
   built in the circuit depending on the port number. */
nr_complex_t circuit::getB (int port, int nr) {
  return MatrixB[(nr - vsource) * size + port];
}

/* Sets the circuits B-MNA matrix value of the given voltage source
   built in the circuit depending on the port number. */
void circuit::setB (int port, int nr, nr_complex_t z) {
  MatrixB[nr * size + port] = z;
}

/* Returns the circuits C-MNA matrix value of the given voltage source
   built in the circuit depending on the port number. */
nr_complex_t circuit::getC (int nr, int port) {
  return MatrixC[(nr - vsource) * size + port];
}

/* Sets the circuits C-MNA matrix value of the given voltage source
   built in the circuit depending on the port number. */
void circuit::setC (int nr, int port, nr_complex_t z) {
  MatrixC[nr * size + port] = z;
}

/* Returns the circuits D-MNA matrix value of the given voltage source
   built in the circuit. */
nr_complex_t circuit::getD (int r, int c) {
  return MatrixD[(r - vsource) * vsources + c - vsource];
}

/* Sets the circuits D-MNA matrix value of the given voltage source
   built in the circuit. */
void circuit::setD (int r, int c, nr_complex_t z) {
  MatrixD[r * vsources + c] = z;
}

/* Returns the circuits E-MNA matrix value of the given voltage source
   built in the circuit. */
nr_complex_t circuit::getE (int nr) {
  return VectorE[nr - vsource];
}

/* Sets the circuits E-MNA matrix value of the given voltage source
   built in the circuit. */
void circuit::setE (int nr, nr_complex_t z) {
  VectorE[nr] = z;
}

/* Returns the circuits I-MNA matrix value of the current source built
   in the circuit. */
nr_complex_t circuit::getI (int port) {
  return VectorI[port];
}

/* Sets the circuits I-MNA matrix value of the current source built in
   the circuit depending on the port number. */
void circuit::setI (int port, nr_complex_t z) {
  VectorI[port] = z;
}

/* Modifies the circuits I-MNA matrix value of the current source
   built in the circuit depending on the port number. */
void circuit::addI (int port, nr_complex_t i) {
  VectorI[port] += i;
}

/* Same as above with different argument type. */
void circuit::addI (int port, nr_double_t i) {
  VectorI[port] += i;
}

/* Returns the circuits Q-HB vector value. */
nr_complex_t circuit::getQ (int port) {
  return VectorQ[port];
}

/* Sets the circuits Q-HB vector value. */
void circuit::setQ (int port, nr_complex_t q) {
  VectorQ[port] = q;
}

/* Returns the circuits J-MNA matrix value of the given voltage source
   built in the circuit. */
nr_complex_t circuit::getJ (int nr) {
  return VectorJ[nr];
}

/* Sets the circuits J-MNA matrix value of the given voltage source
   built in the circuit. */
void circuit::setJ (int nr, nr_complex_t z) {
  VectorJ[nr - vsource] = z;
}

// Returns the circuits voltage value at the given port.
nr_complex_t circuit::getV (int port) {
  return VectorV[port];
}

// Sets the circuits voltage value at the given port.
void circuit::setV (int port, nr_complex_t z) {
  VectorV[port] = z;
}

/* Returns the circuits G-MNA matrix value depending on the port
   numbers. */
nr_complex_t circuit::getY (int r, int c) {
  return MatrixY[r * size + c];
}

/* Sets the circuits G-MNA matrix value depending on the port
   numbers. */
void circuit::setY (int r, int c, nr_complex_t y) {
  MatrixY[r * size + c] = y;
}

/* Modifies the circuits G-MNA matrix value depending on the port
   numbers. */
void circuit::addY (int r, int c, nr_complex_t y) {
  MatrixY[r * size + c] += y;
}

/* Same as above with different argument type. */
void circuit::addY (int r, int c, nr_double_t y) {
  MatrixY[r * size + c] += y;
}

/* Returns the circuits G-MNA matrix value depending on the port
   numbers. */
nr_double_t circuit::getG (int r, int c) {
  return real (MatrixY[r * size + c]);
}

/* Sets the circuits G-MNA matrix value depending on the port
   numbers. */
void circuit::setG (int r, int c, nr_double_t y) {
  MatrixY[r * size + c] = y;
}

/* Returns the circuits C-HB matrix value depending on the port
   numbers. */
nr_complex_t circuit::getQV (int r, int c) {
  return MatrixQV[r * size + c];
}

/* Sets the circuits C-HB matrix value depending on the port
   numbers. */
void circuit::setQV (int r, int c, nr_complex_t qv) {
  MatrixQV[r * size + c] = qv;
}

/* Returns the circuits GV-HB vector value depending on the port
   number. */
nr_complex_t circuit::getGV (int port) {
  return VectorGV[port];
}

/* Sets the circuits GV-HB matrix value depending on the port
   number. */
void circuit::setGV (int port, nr_complex_t gv) {
  VectorGV[port] = gv;
}

/* Returns the circuits CV-HB vector value depending on the port
   number. */
nr_complex_t circuit::getCV (int port) {
  return VectorCV[port];
}

/* Sets the circuits CV-HB matrix value depending on the port
   number. */
void circuit::setCV (int port, nr_complex_t cv) {
  VectorCV[port] = cv;
}

/* This function adds a operating point consisting of a key and a
   value to the circuit. */
void circuit::addOperatingPoint (const char * n, nr_double_t val) {
  operatingpoint * p = new operatingpoint (n, val);
  oper.add (n, p);
}

/* Returns the requested operating point value which has been
   previously added as its double representation.  If there is no such
   operating point the function returns zero. */
nr_double_t circuit::getOperatingPoint (const char * n) {
  operatingpoint * p = oper.get (n);
  if (p != NULL) return p->getValue ();
  return 0.0;
}

/* This function sets the operating point specified by the given name
   to the value passed to the function. */
void circuit::setOperatingPoint (const char * n, nr_double_t val) {
  operatingpoint * p = oper.get (n);
  if (p != NULL)
    p->setValue (val);
  else
    addOperatingPoint (n, val);
}

/* The function checks whether the circuit has got a certain operating
   point value.  If so it returns non-zero, otherwise it returns
   zero. */
int circuit::hasOperatingPoint (char * n) {
  return (oper.get (n)) ? 1 : 0;
}

/* This function adds a characteristic point consisting of a key and a
   value to the circuit. */
void circuit::addCharacteristic (const char * n, nr_double_t val) {
  characteristic * p = new characteristic (n, val);
  charac.add (n, p);
}

/* Returns the requested characteristic value which has been
   previously added as its double representation.  If there is no such
   characteristic value the function returns zero. */
nr_double_t circuit::getCharacteristic (char * n) {
  characteristic * p = charac.get (n);
  if (p != NULL) return p->getValue ();
  return 0.0;
}

/* This function sets the characteristic value specified by the given
   name to the value passed to the function. */
void circuit::setCharacteristic (const char * n, nr_double_t val) {
  characteristic * p = charac.get (n);
  if (p != NULL)
    p->setValue (val);
  else
    addCharacteristic (n, val);
}

/* The function checks whether the circuit has got a certain
   characteristic value.  If so it returns non-zero, otherwise it
   returns zero. */
int circuit::hasCharacteristic (char * n) {
  return (charac.get (n)) ? 1 : 0;
}

// Returns the S-parameter at the given matrix position.
nr_complex_t circuit::getS (int x, int y) { 
  return MatrixS[y + x * size];
}

// Sets the S-parameter at the given matrix position.
void circuit::setS (int x, int y, nr_complex_t z) {
  MatrixS[y + x * size] = z;
}

// Returns the noise-correlation-parameter at the given matrix position.
nr_complex_t circuit::getN (int r, int c) { 
  return MatrixN[c + r * (size + nsources)];
}

// Sets the noise-correlation-parameter at the given matrix position.
void circuit::setN (int r, int c, nr_complex_t z) {
  MatrixN[c + r * (size + nsources)] = z;
}

// Returns the number of internal voltage sources for DC analysis.
int circuit::getVoltageSources (void) {
  return vsources;
}

// Sets the number of internal voltage sources for DC analysis.
void circuit::setVoltageSources (int s) {
  assert (s >= 0);
  vsources = s;
}

// Returns the number of internal noise sources for AC analysis.
int circuit::getNoiseSources (void) {
  return nsources;
}

// Sets the number of internal noise voltage sources for AC analysis.
void circuit::setNoiseSources (int s) {
  assert (s >= 0);
  nsources = s;
}

/* The function returns an internal node or circuit name with the
   given prefix and based on the given circuits name.  The caller is
   responsible to free() the returned string. */
char * circuit::createInternal (const char * prefix, const char * obj) {
  char * n = (char *) malloc (strlen (prefix) + strlen (obj) + 3);
  sprintf (n, "_%s#%s", prefix, obj);
  return n;
}

/* Creates an internal node given the node number as well as the name
   suffix.  An appropriate node name is constructed from the circuits
   name and the suffix. */
void circuit::setInternalNode (int node, const char * suffix) {
  char * n = createInternal (getName (), suffix);
  setNode (node, n, 1);
  free (n);
}

/* This function copies the matrix elements inside the given matrix to
   the internal S-parameter matrix of the circuit. */
void circuit::setMatrixS (matrix s) {
  int r = s.getRows ();
  int c = s.getCols ();
  // copy matrix elements
  if (r > 0 && c > 0 && r * c == size * size) {
    memcpy (MatrixS, s.getData (), sizeof (nr_complex_t) * r * c);
  }
}

/* The function return a matrix containing the S-parameters of the
   circuit. */
matrix circuit::getMatrixS (void) {
  matrix res (size);
  memcpy (res.getData (), MatrixS, sizeof (nr_complex_t) * size * size);
  return res;
}

/* This function copies the matrix elements inside the given matrix to
   the internal noise correlation matrix of the circuit. */
void circuit::setMatrixN (matrix n) {
  int r = n.getRows ();
  int c = n.getCols ();
  // copy matrix elements
  if (r > 0 && c > 0 && r * c == size * size) {
    memcpy (MatrixN, n.getData (), sizeof (nr_complex_t) * r * c);
  }
}

/* The function return a matrix containing the noise correlation
   matrix of the circuit. */
matrix circuit::getMatrixN (void) {
  matrix res (size);
  memcpy (res.getData (), MatrixN, sizeof (nr_complex_t) * size * size);
  return res;
}

/* This function copies the matrix elements inside the given matrix to
   the internal G-MNA matrix of the circuit. */
void circuit::setMatrixY (matrix y) {
  int r = y.getRows ();
  int c = y.getCols ();
  // copy matrix elements
  if (r > 0 && c > 0 && r * c == size * size) {
    memcpy (MatrixY, y.getData (), sizeof (nr_complex_t) * r * c);
  }
}

/* The function return a matrix containing the G-MNA matrix of the
   circuit. */
matrix circuit::getMatrixY (void) {
  matrix res (size);
  memcpy (res.getData (), MatrixY, sizeof (nr_complex_t) * size * size);
  return res;
}

// The function cleans up the B-MNA matrix entries.
void circuit::clearB (void) {
  memset (MatrixB, 0, sizeof (nr_complex_t) * size * vsources);
}

// The function cleans up the C-MNA matrix entries.
void circuit::clearC (void) {
  memset (MatrixC, 0, sizeof (nr_complex_t) * size * vsources);
}

// The function cleans up the D-MNA matrix entries.
void circuit::clearD (void) {
  memset (MatrixD, 0, sizeof (nr_complex_t) * vsources * vsources);
}

// The function cleans up the E-MNA matrix entries.
void circuit::clearE (void) {
  memset (VectorE, 0, sizeof (nr_complex_t) * vsources);
}

// The function cleans up the J-MNA matrix entries.
void circuit::clearJ (void) {
  memset (VectorJ, 0, sizeof (nr_complex_t) * vsources);
}

// The function cleans up the I-MNA matrix entries.
void circuit::clearI (void) {
  memset (VectorI, 0, sizeof (nr_complex_t) * size);
}

// The function cleans up the V-MNA matrix entries.
void circuit::clearV (void) {
  memset (VectorV, 0, sizeof (nr_complex_t) * size);
}

// The function cleans up the G-MNA matrix entries.
void circuit::clearY (void) {
  memset (MatrixY, 0, sizeof (nr_complex_t) * size * size);
}

/* This function can be used by several components in order to place
   the n-th voltage source between node 'pos' and node 'neg' with the
   given value.  Remember to indicate this voltage source using the
   function setVoltageSources(). */
void circuit::voltageSource (int n, int pos, int neg, nr_double_t value) {
  setC (n, pos, +1.0); setC (n, neg, -1.0);
  setB (pos, n, +1.0); setB (neg, n, -1.0);
  setD (n, n, 0.0);
  setE (n, value);
}

/* The function runs the necessary calculation in order to perform a
   single integration step of a voltage controlled capacitance placed
   in between the given nodes.  It is assumed that the appropiate
   charge only depends on the voltage between these nodes. */
void circuit::transientCapacitance (int qstate, int pos, int neg,
                    nr_double_t cap, nr_double_t voltage,
                    nr_double_t charge) {
  nr_double_t g, i;
  int cstate = qstate + 1;
  setState (qstate, charge);
  integrate (qstate, cap, g, i);
  addY (pos, pos, +g); addY (neg, neg, +g);
  addY (pos, neg, -g); addY (neg, pos, -g);
  i = pol * (getState (cstate) - g * voltage);
  addI (pos , -i);
  addI (neg , +i);
}

/* This is the one-node variant of the above function.  It performs
   the same steps for a single node related to ground. */
void circuit::transientCapacitance (int qstate, int node, nr_double_t cap,
                    nr_double_t voltage, nr_double_t charge) {
  nr_double_t g, i;
  int cstate = qstate + 1;
  setState (qstate, charge);
  integrate (qstate, cap, g, i);
  addY (node, node, +g);
  i = pol * (getState (cstate) - g * voltage);
  addI (node , -i);
}

/* The function performs a single integration step of the given charge
   located between the given nodes.  It saves the current
   contributions of the charge itself and considers the polarity of
   the circuit. */
void circuit::transientCapacitanceQ (int qstate, int qpos, int qneg,
                     nr_double_t charge) {
  nr_double_t unused, i;
  int cstate = qstate + 1;
  setState (qstate, charge);
  integrate (qstate, 0, unused, unused);
  i = pol * getState (cstate);
  addI (qpos , -i);
  addI (qneg , +i);
}

/* This is the one-node variant of the above function.  It performs
   the same steps for a single node related to ground. */
void circuit::transientCapacitanceQ (int qstate, int qpos,
                     nr_double_t charge) {
  nr_double_t unused, i;
  int cstate = qstate + 1;
  setState (qstate, charge);
  integrate (qstate, 0, unused, unused);
  i = pol * getState (cstate);
  addI (qpos , -i);
}

/* This function stores the Jacobian entries due to the C = dQ/dV
   value.  The nodes where the charge is located as well as those of
   the voltage dependency, the appropiate capacitance value and the
   voltage across the the controlling branch must be given.  It also
   saves the current contributions which are necessary for the NR
   iteration and considers the polarity of the circuit. */
void circuit::transientCapacitanceC (int qpos, int qneg, int vpos, int vneg,
                     nr_double_t cap, nr_double_t voltage) {
  nr_double_t g, i;
  conductor (cap, g);
  addY (qpos, vpos, +g); addY (qneg, vneg, +g);
  addY (qpos, vneg, -g); addY (qneg, vpos, -g);
  i = pol * (g * voltage);
  addI (qpos , +i);
  addI (qneg , -i);
}

/* This is the one-node variant of the transientCapacitanceC()
   function.  It performs the same steps for a single charge node
   related to ground. */
void circuit::transientCapacitanceC2V (int qpos, int vpos, int vneg,
                       nr_double_t cap, nr_double_t voltage) {
  nr_double_t g, i;
  conductor (cap, g);
  addY (qpos, vpos, +g);
  addY (qpos, vneg, -g);
  i = pol * (g * voltage);
  addI (qpos , +i);
}

/* This is the one-node variant of the transientCapacitanceC()
   function.  It performs the same steps for a single voltage node
   related to ground. */
void circuit::transientCapacitanceC2Q (int qpos, int qneg, int vpos,
                       nr_double_t cap, nr_double_t voltage) {
  nr_double_t g, i;
  conductor (cap, g);
  addY (qpos, vpos, +g); addY (qneg, vpos, -g);
  i = pol * (g * voltage);
  addI (qpos , +i);
  addI (qneg , -i);
}

/* This is the one-node variant of the transientCapacitanceC()
   function.  It performs the same steps for a single voltage node and
   charge node related to ground. */
void circuit::transientCapacitanceC (int qpos, int vpos,
                     nr_double_t cap, nr_double_t voltage) {
  nr_double_t g, i;
  conductor (cap, g);
  addY (qpos, vpos, +g);
  i = pol * (g * voltage);
  addI (qpos , +i);
}

// The function initializes the histories of a circuit having the given age.
void circuit::initHistory (nr_double_t age) {
  nHistories = getSize () + getVoltageSources ();
  histories = new history[nHistories];
  for (int i = 0; i < nHistories; i++) histories[i].setAge (age);
}

// The function deletes the histories for the transient analysis.
void circuit::deleteHistory (void) {
  if (histories != NULL) {
    delete[] histories;
    histories = NULL;
  }
  setHistory (false);
}

// Appends a history value.
void circuit::appendHistory (int n, nr_double_t val) {
  histories[n].append (val);
}

// Returns the required age of the history.
nr_double_t circuit::getHistoryAge (void) {
  if (histories) return histories[0].getAge ();
  return 0.0;
}

/* This function should be used to apply the time vector history to
   the value histories of a circuit. */
void circuit::applyHistory (history * h) {
  tvector<nr_double_t> * t = h->getTvector ();
  for (int i = 0; i < nHistories; i++) histories[i].setTvector (t);
}

// Returns voltage at the given time for the given node.
nr_double_t circuit::getV (int port, nr_double_t t) {
  return histories[port].nearest (t);
}

// Returns current at the given time for the given voltage source.
nr_double_t circuit::getJ (int nr, nr_double_t t) {
  return histories[nr + getSize ()].nearest (t);
}