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["Jon Schmid" <address@hidden>]

Hello,

It seems that putting the diff operator as an argument in the environment ev() call along with the function value causes the derivatives to be computed.  The manuals are kind of light on explaining this functionality, does this work with any operator?

Thanks,
Jon Schmid

On 8/22/07, Jon Schmid <address@hidden> wrote:

Hello,

I was wondering if anyone could tell me how I am misusing the (single quote repeated twice) ' ' operator in TeXmacs, under mathematical input mode.
For Example:

expr: diff( y(t), t, 2) - 5 * diff( y(t), t ) + 6 * y(t);

I want to check the algebra showing e^(5*x) plugged in for y(t) in 'expr' evaluates to 0.  I use an environment call to plug in e^(5*x) for the value of y(t):

ev(expr , y(t):= %e<rsup|(5*t)> );

but this only goes as far as giving the original expr with e^(5*x) plugged in for y(t).  What I would like to see at this point is the result of the two diff() operators acting on their arguments, so that I can see the integer coefficients of e^(5*x) in all three terms, and that they add to 0. 

What should I do to the result of the ev() environment _expression_ to see these steps?  I could always just force a numeric approximation, but I'd rather understand how to control the re-evaluation/execution of the algebra in-between.

Thanks,
Jon Schmid