Re: function applied on equation



laurent couraud wrote:
> Hello all,
> 
> (%i1) eq:a=b$
> (%i2) sqrt(eq);
> (%o2)        sqrt(a) = sqrt(b)    OK very useful
> (%i3) eq^2;
> (%o3)        a^2 = b^2   OK very useful
> (%i4) eq/c;
> (%o4)        a = b    OK very useful
>              -   -
>              c   c
> (%i5) eq*c;
> (%o5)        a c = b c    OK very useful
> (%i6) eq+c;
> (%o6)        c + a = c + b    OK very useful
> 
> But
> 
> (%i4) sin(eq);
> (%o4)        sin(a = b)    ???? The function is applied on full
> equation and not on each members
> 
> 
> This is the case for all trig, inverse trig, exponential, log and power.
> 
> Is this a choice?

I haven't been using maxima very long, but I have noticed that when it
can't understand an expression, it returns the expression unmodified.
What is the mathematical meaning of sin(a = b)?

The following works well though;

		sin(a),eq;
(Returns sin(b))
		sin(b),eq;
doesn't work (returns sin(a)), but this can give the "proper" result if
given as:
		sin(b),solve(eq,b);

Joal Heagney