Scicos

Modeling and Simulation in Scilab/Scicos
by Stephen L. Campbell, Jean-Philippe Chancelier, and Ramine Nikoukhah
Purchase at: Springer or Amazon . ISBN 0-387-27802-8
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Book cover [PDF]
Table of contents [PDF]
Chapter 7: Scicos, Getting started [PDF]

The objective of this book is to provide a tutorial for the use of Scilab/Scicos with a special emphasis on modeling and simulation tools. While it will provide useful information to experienced users it is designed to be accessible to beginning users from a variety of disciplines. Students and academic and industrial scientists and engineers should find it useful.

The book is divided into two parts. The first part concerns Scilab and includes a tutorial covering the language features, the data structures and specialized functions for doing graphics, importing, exporting data and interfacing external routines. It also covers in detail Scilab numerical solvers for ordinary differential equations and differential-algebraic equations. Even though the emphasis is placed on modeling and simulation applications, this part provides a global view of Scilab. The second part is dedicated to modeling and simulation of dynamical systems in Scicos. This type of modeling tool is widely used in industry because it provides a means for constructing modular and reusable models. This part contains a detailed description of the editor and its usage, which is illustrated through numerous examples. All codes used in the book are made available to the reader.


Part I	Scilab

1	General Information	3
1.1	What Is Scilab?	3
1.2	How to Start?	4
1.2.1	Installation	4
1.2.2	First Steps	4
1.2.3	Line Editor	5
1.2.4	Documentation	6
1.3	Typical Usage	6
1.4	Scilab on the Web	7
2	Introduction to Scilab	9
2.1	Scilab Objects	11
2.1.1	Matrix Construction and Manipulation	12
2.1.2	Strings	17
2.1.3	Boolean Matrices	19
2.1.4	Polynomial Matrices	20
2.1.5	Sparse Matrices	21
2.1.6	Lists	22
2.1.7	Functions	26
2.2	Scilab Programming	27
2.2.1	Branching	28
2.2.2	Iterations	29
2.2.3	Scilab Functions	31
2.2.4	Debugging Programs	35
2.3	Input and Output Functions	37
2.3.1	Display of Variables	37
2.3.2	Formatted Input and Output	38
2.3.3	Input Output in Binary Mode	40
2.3.4	Accessing the Host System	42
2.3.5	Graphical User Interface	43
2.4	Scilab Graphics	48
2.4.1	Basic Graphing	48
2.4.2	Graphic Tour	49
2.4.3	Graphics Objects	53
2.4.4	Scilab Graphics and \LaTeX	56
2.4.5	Old Graphics Style	60
2.5	Interfacing	62
2.5.1	Linking Code	63
2.5.2	Writing an Interface	66
2.5.3	Dynamic Loading	69
3	Modeling and Simulation in Scilab	73
3.1	Types of Models	73
3.1.1	Ordinary Differential Equations	73
3.1.2	Boundary Value Problems	74
3.1.3	Difference Equations	75
3.1.4	Differential Algebraic Equations	76
3.1.5	Hybrid Systems	77
3.2	Simulation Tools	78
3.2.1	Ordinary Differential Equations	78
3.2.2	Boundary Value Problems	90
3.2.3	Difference Equations	95
3.2.4	Differential Algebraic Equations	98
3.2.5	Hybrid Systems	100
4	Optimization	107
4.1	Comments on Optimization and Solving Nonlinear Equations	107
	Constraints	107
	Nonlinear Equation Solving	108
4.2	General Optimization	108
4.3	Solving Nonlinear Equations	112
4.4	Nonlinear Least Squares	113
	leastsq	113
	lsqrsolve	114
4.5	Parameter Fitting	117
4.6	Linear and Quadratic Programming	119
4.6.1	Linear Programs	119
4.6.2	Quadratic Programs	120
4.6.3	Semidefinite Programs	120
4.7	Differentiation Utilities	120
4.7.1	Higher Derivatives	122
5	Examples	125
5.1	Modeling and Simulation of an N-Link Pendulum	125
5.1.1	Equations of Motion of the N-Link Pendulum	126
5.1.2	Generated Code and Simulation	130
5.1.3	Maple Code	133
5.2	Modeling and Simulation of a Car	135
5.2.1	Basic Model	135
5.2.2	Equations of Motion	136
5.2.3	Simulation Model	138
	Discrete States	138
5.2.4	Scilab Implementation	139
5.2.5	Simulation Result	141
5.3	Open-Loop Control to Swing Up a Pendulum	142
5.3.1	Model	142
5.3.2	Control Problem Formulation	142
5.3.3	Optimization Problem	143
5.3.4	Implementation in Scilab	145
5.4	Parameter Fitting and Implicit Models	147
5.4.1	Mathematical Model	148
5.4.2	Scilab Implementation	148

Part II	Scicos	157

6	Introduction	159
7	Getting Started	163
7.1	Construction of a Simple Diagram	163
7.1.1	Running Scicos	163
7.1.2	Editing a Model	163
7.1.3	Diagram Simulation	165
7.1.4	Changing Block Parameters	166
	SIR Model for Spread of Disease	167
	Chaotic Dynamics of a Rössler Attractor	168
7.2	Symbolic Parameters and Context	169
	Remark	173
7.3	Hierarchy	173
7.3.1	Placing a Super Block in a Diagram	173
7.3.2	Editing a Super Block	174
7.4	Save and Load	175
7.4.1	Scicos File Formats	175
7.4.2	Super Block and Palette	176
7.5	Synchronism and Special Blocks	176
8	Scicos Formalism	179
8.1	Activation Signal	179
8.1.1	Block Activation	179
8.1.2	Activation Generation	181
8.2	Inheritance	182
8.3	Always Active Blocks	183
8.4	Constant Blocks	184
8.5	Conditional Blocks	184
9	Scicos Blocks	189
9.1	Block Behavior	189
9.1.1	External Activation	189
	Event Activation	190
	Continuous-Time Activation	191
	Mode and Zero-Crossing	191
9.1.2	Always Activation	191
9.1.3	Internal Zero-Crossing	192
9.2	Blocks Inside Palettes	192
9.3	Modifying Block Parameters	193
9.4	Super Block and Scifunc	193
9.4.1	Super Blocks	193
9.4.2	Scifunc	194
9.5	Constructing New Basic Blocks	194
9.5.1	Interfacing Function	195
	Syntax	195
	Parameter job	196
	Example: the Interfacing Function of the Absolute Value Block	196
9.5.2	Computational Function	197
	Examples	201
	Example	206
9.5.3	Saving New Blocks	207
9.6	Constructing and Loading a New Palette	207
10	Examples	209
10.1	Predator Prey Model	209
10.2	Control Application	210
10.3	Signal Processing Application	213
10.4	Queuing Systems	216
10.5	Neuroscience Application	218
10.6	A Fluid Model of TCP-Like Behavior	220
10.7	Interactive GUI	221
11	Batch Processing in Scilab	227
11.1	Piloting Scicos via Scilab Commands	227
11.1.1	Function scicosim	228
11.1.2	Function scicos_simulate	232
11.2	Data Sharing	233
11.2.1	Context Variables	234
11.2.2	Input/Output Files	234
11.2.3	Global Variables	236
11.3	Examples	237
11.4	Steady-State Solution and Linearization	243
11.4.1	Scilab Function steadycos	247
11.4.2	Scilab Function lincos	248
12	Code Generation	253
12.1	Code Generation Procedure	253
12.2	Limitations	257
12.2.1	Continuous-Time Activation	257
12.2.2	Synchronicism	258
12.3	A Look Inside	258
	Diagram Construction	258
	Compilation	259
	Code Generation	260
	Block Construction	260
	Substitution	260
12.4	Some Pitfalls	260
12.5	Applications	263
13	Debugging	267
13.1	Error Messages	267
13.1.1	Block Errors	267
13.1.2	Errors During Numerical Integration	268
13.1.3	Other Errors	269
	Initial Conditions not Converging	269
	Cannot Allocate Memory	269
13.2	Debugging Tools	269
13.3	Examples	270
13.3.1	Log File	271
13.3.2	Animation	271
14	Implicit Scicos and Modelica	273
14.1	Introduction	273
14.2	Internally Implicit Blocks	275
14.3	Implicit Blocks	275
14.3.1	Scicos Editor	276
14.3.2	Scicos Compiler	276
14.3.3	Block Construction	276
14.4	Example	277
A	Inside Scicos	281
A.1	Scicos Editor	281
A.1.1	Main Editor Function	281
	Example	282
A.1.2	Structure of scs_m	283
	Scicos Block	285
	Scicos Link	286
A.2	Scicos Complier	286
A.2.1	First Compilation Stage	286
A.2.2	Second Compilation Stage	287
A.2.3	Structure of %cpr	287
A.2.4	Partial Compilation	290
A.3	Scicos Simulator	291
B	Scicos Blocks of Type 5	293
B.1	Type 5 Block for the Bouncing Ball Example	293
B.2	Animation Block for the Cart Pendulum Example	294
C	Animation Program for the Car Example	299
D	Extraction Program for the LaTeX Graphic Example	301
E	Maple Code Used for Modeling the N-Link Pendulum	303
	References	307
	Index	309