% BISECTION ALGORITHM 2.1
%
% To find a solution to f(x) = 0 given the continuous function
% f on the interval [a,b], where f(a) and f(b) have
% opposite signs:
%
% INPUT: endpoints a,b; tolerance TOL;
% maximum number of iterations NO.
%
% OUTPUT: approximate solution p or
% a message that the algorithm fails.
syms('OK','A','B','X','FA','FB','TOL','NO','FLAG','NAME','OUP','I')
syms('C','P','FP','x','s')
TRUE = 1;
FALSE = 0;
fprintf(1,'This is the Bisection Method.\n');
fprintf(1,'Input the function F(x) in terms of x\n');
fprintf(1,'For example: cos(x)\n ');
s = input(' ','s');
F = inline(s,'x');
OK = FALSE;
while OK == FALSE
fprintf(1,'Input endpoints A < B on separate lines\n');
A = input(' ');
B = input(' ');
if A > B
X = A;
A = B;
B = X;
end
if A == B
fprintf(1,'A cannot equal B\n');
else
FA = F(A);
FB = F(B);
if FA*FB > 0
fprintf(1,'F(A) and F(B) have same sign\n');
else
OK = TRUE;
end
end
end
OK = FALSE;
while OK == FALSE
fprintf(1,'Input tolerance\n');
TOL = input(' ');
if TOL <= 0
fprintf(1,'Tolerance must be positive\n');
else
OK = TRUE;
end
end
OK = FALSE;
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