/************************************************************************
    Copyright (C) 2003, 2004, 2006, 2007 Jaime E. Villate <villate@fe.up.pt>

    This program 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 of the License, or
    (at your option) any later version.

    This program 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 program; if not, write to the Free Software
    Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA

$Id: dynamics.mac,v 1.6 2010-04-20 12:55:46 villate Exp $
***********************************************************************/

load("complex_dynamics.lisp")$
load("plotdf.lisp")$

/************************************************************************
 Function evolution

    Description: Maxima program to draw orbits of one-dimensional mappings
    Usage:
      evolution(fun, initial, n, ..., [options], ...);
    "fun" must be an expression which depends only on one variable.
    "initial" is the initial value for that variable, and n is the number
    of steps. [options] can be any options accepted by plot2d.
*/

evolution(fun, initial, n, [options]) :=
  block
  ([z:initial, data: [[0, initial]], kwds: [], plot: numer: true, float: true],
    if length(listofvars(fun)) # 1 then
           error("fun should depend on one variable"),
    for i thru n do
      (z: ev(fun, listofvars(fun)[1]=z),
       if not numberp(z) then
                 error("The function gave a non-numerical value:", z),
       data: cons([i, z], data)),
    for i thru length(options) do
      (if not listp(options[i]) then error("Wrong option", options[i]),
       kwds: cons(options[i][1], kwds)),
    if not member('x,kwds) then options: cons(['x, -0.5, n+0.5],options),
    if not member('xlabel,kwds) then options: endcons(['xlabel, "n"],options),
    if not member('ylabel,kwds) then
          options: endcons(['ylabel,sconcat(listofvars(fun)[1],"(n)")],options),
    if not member('style,kwds) then options: endcons(['style,'points],options),
    options: cons(['discrete, data], options),
    apply(plot2d, options))$

/************************************************************************
 Function staircase

    Description: Maxima program to draw staircase diagrams of
                 one-dimensional mappings
    Usage:
      staircase(fun, initial, n, [options]);
    "fun" must be an expression which depends only on one variable.
    "initial" is the initial value for that variable, and n is the number
    of steps. [options] can be any options accepted by plot2d.
*/

staircase(fun, initial, n, [options]) :=
  block
  ([zf, z:initial, z1:initial, z2:initial, stair:[[initial, initial]],
    kwds: [], numer: true, float: true],
    if length(listofvars(fun)) # 1 then
           error("fun should depend on one variable"),
    for i thru n do
      (zf: ev(fun, listofvars(fun)[1]=z),
       if not numberp(zf) then
                 error("The function gave a non-numerical value:", zf),
       stair: append(stair, [[z, zf], [zf, zf]]),
       z: zf,
       if z < z1 then z1: z,
       if z > z2 then z2: z),
    for i thru length(options) do
      (if not listp(options[i]) then error("Wrong option", options[i]),
       kwds: cons(options[i][1], kwds)),
    if not member(listofvars(fun)[1],kwds) then 
       options: cons([listofvars(fun)[1],
                        4*(1.1*z1-.1*z2)/3,4*(1.1*z2-.1*z1)/3],options),
    if not member('y,kwds) then 
       options: endcons(['y,1.1*z1-.1*z2,1.1*z2-.1*z1],options),
    if not member('xlabel,kwds) then
       options: endcons(['xlabel,sconcat(listofvars(fun)[1],"(n)")],options),
    if not member('ylabel,kwds) then
       options: endcons(['ylabel,sconcat(listofvars(fun)[1],"(n+1)")],options),
    if not member('legend,kwds) then options: endcons(['legend,false],options),
    options: cons([['discrete, stair], fun, listofvars(fun)[1]], options),
    apply(plot2d, options))$

/************************************************************************
 Function evolution2d

    Description: Maxima program to show the evolution of a two-dimensional
                 discrete dynamical system in a 2-dimensional graph.
    Usage:
      evolution2d([fun1, fun2], [u, v], [u0, v0], n, ..., [options], ...);

    fun1 and fun2 must be expressions which depend only on two variables
    (u and v) named on the second list. The third list must give two
    initial numerical values for the two variables. n is the number of
    points to be shown. The options can be any accepted by plot2d.
*/

evolution2d(fun, state, initial, n, [options]) :=
  block
  ([x: initial[1], y: initial[2], xaux, data: [],
    fx: false, fy: false, kwds: [], numer: true, float: true],
    if length(listofvars(fun)) >2 then
           error("fun should depend on two variables."),
    for i thru length(options) do
      (if not listp(options[i]) then error("Wrong option", options[i]),
       if options[i][1]=state[1] then
          (x1: options[i][2],
           x2: options[i][3],
           options[i][1]:'x,
           fx: true),
       if options[i][1]=state[2] then
          (y1: options[i][2],
           y2: options[i][3],
           options[i][1]: 'y,
           fy: true),
       kwds: cons(options[i][1], kwds)),
    for i thru n do
      (if (fx and fy)
        then
          (if ((y >= y1) and (y <= y2) and (x >= x1) and (x <= y2)) then
              data: cons([x, y], data))
        else
          (data: cons([x, y], data)),
       xaux: ev(fun[1], state[1]=x, state[2]=y),
       if not numberp(xaux) then
                 error("Function",fun[1],"gave a non-numerical value:", xaux),
       y: ev(fun[2], state[1]=x, state[2]=y),
       if not numberp(y) then
                 error("The function",fun[2],"gave a non-numerical value:", y),
       x: xaux),
    if not member('xlabel,kwds) then
       options: endcons(['xlabel,string(state[1])],options),
    if not member('ylabel,kwds) then
       options: endcons(['ylabel,string(state[2])],options),
    if not member('style,kwds) then options: endcons(['style,'points],options),
    options: cons(['discrete, data], options),
    print("Graph passed to plot2d..."),
    apply(plot2d, options))$

/************************************************************************
 Function chaosgame

    Description: Maxima program to play the "chaos game".
    Usage:
      chaosgame([[x1,y1]...[xm,ym]], [x0,y0], beta, n, [options]);

    where [x0,y0] are the coordinates of the initial point, [x1,y1]
    ... [xm,ym] are the attracting points, beta is the ratio of the
    final to initial distance from the attracting point, and n the
    number of points to show.
*/

chaosgame(point,p0,b,n,[options]) :=
block
  ([p:ev(p0,numer), j, m:length(point), data: [p0], kwds: [],
    xlabel, ylabel, numer:true, float:true],
    if length(p0) # 2 then
        error("Initial point",p0,"should be a list with 2 components"),
    if not (numberp(p[1]) and numberp(p[2])) then
        error("The components of the initial point", p,"should be numbers"),
    for i thru m do
        if length(point[i]) # 2 then
         error("Point",point[i],"should be a list with 2 components"),
    for i thru n do
       (j: random(m) + 1,
        p: ev(point[j] + b*(p-point[j]), numer),
        if not (numberp(p[1]) and numberp(p[2])) then
              error("Non-numerical coordinates were obtained:", p),
       data: cons(p, data)),
    for i thru length(options) do
      (if not listp(options[i]) then error("Wrong option", options[i]),
       kwds: cons(options[i][1], kwds)),
    if not member('xlabel,kwds) then
       (xlabel: sconcat("The chaos game with ",m," points"),
        options: endcons(['xlabel,xlabel],options)),
    if not member('ylabel,kwds) then
       (ylabel: sconcat("contraction factor: ",b),
        options: endcons(['ylabel,ylabel],options)),
    if not member('style,kwds) then options: endcons(['style,'points],options),
    options: cons(['discrete, data], options),
    apply(plot2d, options))$

/************************************************************************
 Function ifs

    Description: Maxima program to create 2-d fractals using Barnley's
                 IFS (Iterated Function Systems) method.
    Usage:
      ifs([r1,...,rm], [A1,...,Am], [p1,...,pm]], p0, n, [options]);

    where r1,...,rm are cumulative weights for the attracting points.
    For instance if there are 3 points with probabilities 0.2, 0.5 and
    0.3, you can use [2,7,10].
    A1,...,Am, are the matrices for the m attracting points and
    p1,...,pm are the 2D coordinates of those points. p0 are the 2D
    coordinates of the initial point and n the number of points to be
    shown.
*/

ifs(prob, mat, point, p0, n, [options]) :=
block 
  ([p:ev(p0,numer), s, r, w:last(prob), data:[p0], xlabel, kwds: [],
    m:length(prob), plist, numer:true, float:true],
    if length(p0) # 2 then
        error("Initial point",p0,"should be a list with 2 components"),
    if not (numberp(p[1]) and numberp(p[2])) then
        error("The components of the initial point", p,"should be numbers"),
    if not ((length(mat)=m) and (length(point)=m)) then
        error("There should be the same number of probabilities, matrices and points"),
    for i thru m do
       (if length(point[i]) # 2 then
           error("Point",point[i],"should be a list with 2 components"),
        if not numberp(prob[i]) then
           error("Cumulative probability",prob[i],"should be a number"),
        if not ((length(mat[i])=2) and (length(mat[i][1])=2)) then
           error("Matrix",mat[i],"should be a 2x2 matrix")),
    for i thru n do
       (r: random(w) + 1,
        s: 0,
        for j while (r-prob[j]) > 0 do s:j,
        p: ev(mat[s+1].p + point[s+1], numer),
        plist: first(transpose(p)),
        if not (numberp(plist[1]) and numberp(plist[2])) then
           error("Non-numerical coordinates were obtained:", plist),
        data: cons(plist, data)),
    for i thru length(options) do
       (if not listp(options[i]) then error("Wrong option", options[i]),
        kwds: cons(options[i][1], kwds)),
    if not member('xlabel,kwds) then
       (xlabel: sconcat("Iterated Function System of ",m," transformations"),
        options: endcons(['xlabel,xlabel],options)),
    if not member('ylabel,kwds) then options: endcons(['ylabel,""],options),
    if not member('style,kwds) then options: endcons(['style,'points],options),
    options: cons(['discrete, data], options),
    apply(plot2d, options))$

/************************************************************************
 Function orbits

    Description: Maxima program to draw orbit diagrams (also dubbed as
                 bifurcation diagrams) for first-order discrete
                 dynamical systems
    Usage:
      orbits(f, initial, n1, n2, [u, u0, uf], ..., [options], ...)

    It will plot the orbits diagram for a family of first order discrete
    dynamical system, with a parameter.
    f must be an expression which depends only on one variable and
    the parameter. The parameter must be named in the first component of
    the list [u, u0, uf] (in this example it would be u) that sets up
    the range of the variation for the parameter, from u0, uf. The initial
    value of the parameter can be smaller than the final value, in the
    cases when the bifurcations appear as the parameter decreases.
    "initial" is an initial value for the state variable.
    The parameter will be represented in the horizontal axis; the range of
    the parameter will be divided by the value given by the nticks option,
    or by 200 if that option is not used. For each value of the parameter,
    the system will be left to evolve during n1 steps, and then the next
    n2 steps will be plotted in the vertical axis.
    The program tuns faster if a range is given to the vertical axis.
    By default, the vertical scale is divide in 600 pixels. That number
    can be changed with the option pixels, for instance, [pixels, 700].
*/

orbits(f, y0, n1, n2, domain, [options]) :=
block
 ([x, y, data: [], y1, y2, yflag: false, kwds: [], var, points, plot: [],
   x0: domain[2], s, n, pixels: 600, numer:true, float: true],
   var: listofvars(f),
   var: delete(domain[1],var),
    if length(listofvars(fun)) >2 then
           error("f should depend on two variables."),
    for i thru length(options) do
      (if not listp(options[i]) then error("Wrong option", options[i]),
       if options[i][1]=var[1] then
          (y1: options[i][2],
           y2: options[i][3],
           if not y1 < y2 then
           error("The first number has to be smaller than the second in:",options[i]),
           options[i][1]: 'y,
           yflag: true),
       if options[i][1]='nticks then
          (if integerp(options[i][2]) then
              n: options[i][2]
           else
              error("Option nticks should have an integer value")),
       if options[i][1]='pixels then
          (pixels: options[i][2],
           delete(options[i],options))
       else
          plot: endcons(options[i], plot),
       kwds: cons(options[i][1], kwds)),
   if  not (member('nticks,kwds) and integerp(n)) then n: 200,
   s: (domain[3] - domain[2])/n,
   if yflag then
     (for i:0 thru n do
         (x: x0+i*s,
          y: y0,
          points: [],
          for j thru n1 do
             (y: ev(f, domain[1]=x, var[1]=y),
              if not numberp(y) then
                 error("The function gave a non-numerical value:", y)),
          for j thru n2 do
             (y: ev(f, domain[1]=x, var[1]=y),
              if ((y >= y1) and (y <= y2)) then
                 (k: entier(pixels*(y-y1)/(y2-y1))+1,
                  if k>pixels then k: pixels,
                  if not member(k, points) then points: cons(k, points))),
          for j thru length(points) do
              data: cons([x,(y2-y1)*(points[j]-0.5)/pixels+y1], data)))
   else
     (for i:0 thru n do
         (x: x0+i*s,
          y: y0,
          for j thru (n1+n2)/2 do
             (y: ev(f, domain[1]=x, var[1]=y),
              if not numberp(y) then
                 error("The function gave a non-numerical value:", y),
              if not yflag then
                 (y1:y, y2:y, yflag: true)
              else
                 (if y<y1 then y1: y,
                  if y>y2 then y2: y))),
      if not y1 < y2 then error("It was not possible to find any points"),
      for i:0 thru n do
         (x: x0+i*s,
          y: y0,
          points: [],
          for j thru n1 do y: ev(f, domain[1]=x, var[1]=y),
          for j thru n2 do
             (y: ev(f, domain[1]=x, var[1]=y),
              if ((y >= y1) and (y <= y2)) then
                 (k: entier(pixels*(y-y1)/(y2-y1))+1,
                  if k>pixels then k: pixels,
                  if not member(k, points) then points: cons(k, points))),
          for j thru length(points) do
              data: cons([x,(y2-y1)*(points[j]-0.5)/pixels+y1], data))),
   if (length(data) > 0) then
      (if not member('x,kwds) then
	  (if domain[3] > domain[2] then
              plot: cons(['x,domain[2],domain[3]],plot)
           else
              plot: cons(['x,domain[3],domain[2]],plot)),
       if not member('xlabel,kwds) then
          plot: endcons(['xlabel,string(domain[1])],plot),
       if not member('ylabel,kwds) then
          plot: endcons(['ylabel,string(var[1])],plot),
       if not member('style,kwds) then plot:endcons(['style,'points],plot),
       plot: cons(['discrete, data], plot),
       print("Graph passed to plot2d..."),
       apply(plot2d, plot)))$

