2010/3/26 Abdul Rahman Riza
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Thank you Stefan,
That exactly what I wanted.
I am wondering if octave able to plot 2 function f(x) and g(x) simultaneously where 0 < x < 26
Part of it:
define f(x) , f'(x) , f''(x) , solve f'(x)=0, display solution , plot everything in one graph:
x=0:.1:26;
function y=f(x) y=1./((206./x)+1.7*x+5.2); endfunction
function dx=dx(x) dx=(f(x+1e-5)-f(x))/1e-5; endfunction % differentiate to find maximum
function d2x=d2x(x) d2x=(dx(x+1e-5)-dx(x))/1e-5; endfunction % differentiate again for check if max or min
xaxis=zeros(1,length(x)); % hack inexpertly :-) : line at y=0
xmax = fsolve('dx',1) ; % find extremes
xmax % display solution
plot( x,xaxis , xmax*ones(1,2),[-.0095,.025],';xmax;' , x,f(x),';f(x);' , x,5*dx(x),';dx(x);' , x,10*d2x(x),';d2x(x);' ); % plot them all
Kind of fun, actually :-D
cheers, Stefan