buggish feature of Plot ???
- To: mathgroup at yoda.physics.unc.edu
- Subject: buggish feature of Plot ???
- From: wmm at chem.wayne.edu (Martin McClain)
- Date: Tue, 2 Mar 93 13:29:47 EST
The Plot operator seems to suffer a lot from its HoldAll attribute.
Blachman gives as example (p.216) where it draws, without warning, a plot
that seems plainly wrong to humans:
s = 2x/(10x+5);
Plot[Numerator[s],{x,0,5}];
There are other less disturbing examples where it fails to produce a plot
from a command that seems quite clear. The fix in all cases is the same;
namely, an Evaluate which overrides the HoldAll attribute of Plot:
Plot[Evaluate[Numerator[s]],{x,0,5}].
My question: Why does Plot have the HoldAll attribute? What would happen
if I unprotected Plot and took HoldAll away permanently? Can anyone give
an example of misbehaviour if this is done ?