%% HOW DO I DO THAT IN MATLAB SERIES?
% In this series, I am answering questions that students have asked
% me about MATLAB. Most of the questions relate to a mathematical
% procedure.
%% TOPIC
% How do I solve a nonlinear equation if I need to set it up?
%% SUMMARY
% Language : Matlab 2008a;
% Authors : Autar Kaw;
% Mfile available at
% http://numericalmethods.eng.usf.edu/blog/integration.m;
% Last Revised : March 28, 2009;
% Abstract: This program shows you how to solve a nonlinear equation
% that needs to set up as opposed that is just given to you.
clc
clear all
%% INTRODUCTION
disp('ABSTRACT')
disp(' This program shows you how to solve')
disp(' a nonlinear equation that needs to be setup')
disp(' ')
disp('AUTHOR')
disp(' Autar K Kaw of http://autarkaw.wordpress.com')
disp(' ')
disp('MFILE SOURCE')
disp(' http://numericalmethods.eng.usf.edu/blog/nonlinearequation.m')
disp(' ')
disp('LAST REVISED')
disp(' April 17, 2009')
disp(' ')
%% INPUTS
% Solve the nonlinear equation where you need to set up the equation
% For example to find the depth 'x' to which a ball is floating in water
% is based on the following cubic equation
% 4*R^3*S=3*x^2*(R-x/3)
% R= radius of ball
% S= specific gravity of ball
% So how do we set this up if S and R are input values
S=0.6
R=0.055
%% DISPLAYING INPUTS
disp('INPUTS')
func=[' The equation to be solved is 4*R^3*S=3*x^2*(R-x/3)'];
disp(func)
disp(' ')
%% THE CODE
% Define x as a symbol
syms x
% Setting up the equation
C1=4*R^3*S
C2=3
f=[num2str(C1) '-3*x^2*(' num2str(R) '-x/3)']
% Finding the solution of the nonlinear equation
soln=solve(f,x);
solnvalue=double(soln);
%% DISPLAYING OUTPUTS
disp('OUTPUTS')
for i=1:1:length(solnvalue)
fprintf('\nThe solution# %g is %g',i,solnvalue(i))
end
disp(' ')