Re: how to subs t.i with i*t.i

10 Jul 2003

      Hi!

On Thu, Jul 10, 2003 at 05:11:01PM +0800, Yong Xiao wrote:
...
Hi, it seems that the following lines
ex e1 = indexed(t,i); 
e1.subs(indexed(t,idx(i_,3))==idx(i_,3).get_value()*indexed(t,idx(i_,3)));
,where i and i_ are idx and wildcard objects respectively, doesn't 
substitute t.i with i*t.i.
Hm? This works for me:

    symbol t("t");
    idx i(symbol("i"), 3);
    ex e1 = indexed(t, i);
    ex i_ = wild();
    ex e2 = e1.subs(indexed(t, idx(i_, 3)) == i_ * indexed(t, idx(i_, 3)));
    cout << e1 << " -> " << e2 << endl;
     // prints "t.i -> i*t.i"

Perhaps you forgot that subs() returns its result as a new expression?

Bye,
Christian

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  / Physics is an algorithm
\/ http://www.uni-mainz.de/~bauec002/

Re: how to subs t.i with i*t.i

Christian Bauer