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Diffstat (limited to 'chaos/src/chua.hpp')
| -rw-r--r-- | chaos/src/chua.hpp | 165 |
1 files changed, 165 insertions, 0 deletions
diff --git a/chaos/src/chua.hpp b/chaos/src/chua.hpp new file mode 100644 index 0000000..7669a24 --- /dev/null +++ b/chaos/src/chua.hpp @@ -0,0 +1,165 @@ +// +// +// chaos~ +// Copyright (C) 2004 Tim Blechmann +// +// 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; see the file COPYING. If not, write to +// the Free Software Foundation, Inc., 59 Temple Place - Suite 330, +// Boston, MA 02111-1307, USA. + +#include "ode_base.hpp" + +// chua system: dx1/dt = alpha * (x2 - x1 - h(x1)) +// dx2/dt = x1 - x2 + x3 +// dx3/dt = - beta * x2 +// +// with h(x) = b*x + a - b (for x > 1) +// a*x (for -1 <= x <= 1 +// b*x - a + b (for x < -1) +// +// taken from Viktor Avrutin: lecture notes + +class chua: + public ode_base<3> +{ +public: + chua() + { + CHAOS_PAR_INIT(method,2); + CHAOS_PAR_INIT(dt,0.05); + + CHAOS_SYS_INIT(x1,1,1); + CHAOS_SYS_INIT(x2,1,1); + CHAOS_SYS_INIT(x3,1,1); + + CHAOS_PAR_INIT(a,140); + CHAOS_PAR_INIT(b,30); + CHAOS_PAR_INIT(alpha,30); + CHAOS_PAR_INIT(beta,30); + } + + virtual void m_system(data_t* deriv, data_t* data) + { + data_t x1 = data[0]; + data_t x2 = data[1]; + data_t x3 = data[2]; + + data_t a = CHAOS_PARAMETER(a), b = CHAOS_PARAMETER(b); + + data_t h; + + if (x1 > 1) + h = b*x1 + a - b; + else if (x1 < -1) + h = b*x1 - a + b; + else + h = a*x1; + + deriv[0] = CHAOS_PARAMETER(alpha) * (x2 - x1 - h); + deriv[1] = x1 - x2 + x3; + deriv[2] = - CHAOS_PARAMETER(beta) * x2; + } + + virtual void m_verify() + { + data_t x1 = m_data[0]; + data_t x2 = m_data[1]; + data_t x3 = m_data[2]; + + if ( std::abs(x3) < 1e-10) + x3 = 0; + + if (x1 == 0 && x2 == 0 && x3 == 0) /* fixpoint at (0,0,0) */ + { + reset(); + return; + } + else + { + data_t c = m_c; + if (m_c) + { + data_t mc = - c; + if (x1 == c && x3 == mc) /* fixpoint at (c,0,-c) */ + { + reset(); + return; + } + if (x1 == mc && x3 == c) /* fixpoint at (-c,0,c) */ + { + reset(); + return; + } + } + } + } + + inline void reset() + { + m_data[0] = rand_range(-1,1); + m_data[1] = rand_range(-1,1); + m_data[2] = rand_range(-1,1); + } + + CHAOS_SYSVAR_FUNCS(x1, 0); + CHAOS_SYSVAR_FUNCS(x2, 1); + CHAOS_SYSVAR_FUNCS(x3, 2); + + /* due to stability issues, we hook into the predicates */ + data_t m_c; + bool m_pred_a(data_t a) + { + data_t b = CHAOS_PARAMETER(b); + m_c = (b - a) / (b + 1); + return true; + } + + bool m_pred_b(data_t b) + { + if (b == -1) + m_c = 0; + else + { + data_t a = CHAOS_PARAMETER(a); + m_c = (b - a) / (b + 1); + } + return true; + } + + CHAOS_SYSPAR_FUNCS_PRED(a, m_pred_a); + CHAOS_SYSPAR_FUNCS_PRED(b, m_pred_b); + CHAOS_SYSPAR_FUNCS(alpha); + CHAOS_SYSPAR_FUNCS(beta); +}; + + +#define CHUA_CALLBACKS \ +ODE_CALLBACKS; \ +CHAOS_SYS_CALLBACKS(alpha); \ +CHAOS_SYS_CALLBACKS(beta); \ +CHAOS_SYS_CALLBACKS(a); \ +CHAOS_SYS_CALLBACKS(b); \ +CHAOS_SYS_CALLBACKS(x1); \ +CHAOS_SYS_CALLBACKS(x2); \ +CHAOS_SYS_CALLBACKS(x3); + +#define CHUA_ATTRIBUTES \ +ODE_ATTRIBUTES; \ +CHAOS_SYS_ATTRIBUTE(a); \ +CHAOS_SYS_ATTRIBUTE(b); \ +CHAOS_SYS_ATTRIBUTE(alpha); \ +CHAOS_SYS_ATTRIBUTE(beta); \ +CHAOS_SYS_ATTRIBUTE(x1); \ +CHAOS_SYS_ATTRIBUTE(x2); \ +CHAOS_SYS_ATTRIBUTE(x3); |