Symbolic package: Difference between revisions

Symbolic package (edit)

779 bytes added , 6 July 2015

17

edits

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      [-0.777688831121563, -0.7776888311215626]
      [0.22911205809043574, 0.2291120580904359]
+</source>
+* '''Demo of inputting a function at the input prompt and making an Anonymous function.'''
+<source lang="octave">
+# This prog. shows how to take a
+# sring input and make it into an anonymous function
+# this uses the symbolic pkg.
+disp("Example input")
+disp("x^2 + 3*x - 1 + 5*x*sin(x)")
+str_fucn=input("please enter your function  ","s")
+fucn_sym=sym(str_fucn)
+f=function_handle(fucn_sym)
+# now back to symbolic
+syms x;
+ff=formula(f(x));
+% now calculate the derivative of the function
+ffd=diff(ff);
+% and convert it back to an Anonymous function
+df=function_handle(ffd)
+% now lets do the second derivative
+ffdd=diff(ffd);
+ddf=function_handle(ffdd)
+% and now plot them all
+x1=-2:.0001:2;
+plot(x1,f(x1),x1,df(x1),x1,ddf(x1))
+grid minor on
+legend("f","f '", "f '' ")
 </source>