No Error in Mathematica!
- To: mathgroup at yoda.physics.unc.edu
- Subject: No Error in Mathematica!
- From: puglisi at settimo.italtel.it
- Date: Mon, 8 Nov 93 16:43:25 MST
John Writes: I just starting playing with Mathematica and I cannot seem to resolve the following output. In[1]:= x=b Out[1]= b In[2]:= x^2 Out[2]= b^2 (* as I would expect) In[3]:= x^2/.x->a Out[3]= a^2 In[4]:= x=2 Out[4]= 2 In[5]:= x^2/.x->7 Out[5]= 4 What is going on? considering output %3 I would have thought that %5 would be 49 ----------------------------------------------------- The behavior observed is no error,it is the expected one from Mathematica. What happens here is that x=2, and x^2/.x->7 tries to replace x with the value 7 in the constant function 2^2==4. Another way to put it is that Mathematica does symbolic computation, but when it sees a number understand it as a number. Hint: Type ?x after each new input line. Ciao Alberto Puglisi ITALTEL Central Research Laboratories, DRSC-IS CLTB 20019 Castelletto di Settimo Milanese (Milano) Italy phone: (+39)(2)4388-8299 fax: (+39)(2)4388-7989 e-mail: puglisi at settimo.italtel.it