Use of ev() with diff



On 8/02/2011 5:58 AM, Ron Wiltshire wrote:
> Hello
>
> I am currently using wxMaxima 0.8.3a for Mac having used Macsyma for many years. I find that the function
>
> 	ev(sin(x),diff)  does not return cos(x)
>
> 	although
>
> 	ev(2*(x+y),expand) will return 2x+2y.
>
> May be I am doing something wrong or perhaps there is a problem with ev(....., diff). Please can you advise?
>
>
>
> With kind regards - Ron Wiltshire
>
You are doing something wrong.  Perhaps these examples will help.

(%i1) diff(sin(x),x);
(%o1)                               cos(x)
(%i2) 'diff(sin(x),x);
                                   d
(%o2)                             -- (sin(x))
                                   dx
(%i3) ev('diff(sin(x),x));
                                   d
(%o3)                             -- (sin(x))
                                   dx
(%i4) ev('diff(sin(x),x),diff);
(%o4)                               cos(x)