thanks jakubi,

this is a very good link to the Matlab function, actually.

Let me explain how the inf and -inf can be used. Consider the following:

> xmin:=-2*Pi: xmax:=2*Pi:
> plot(cos(x), x=xmin..xmax);

Maple automatically selects the maximum and minimum values along the y-axis. For this specific example, I can reproduce the look of the plot by doing the following (Maple13/classic):

> ymin:=-1.05: ymax:=1.05:
> plot(cos(x), x=xmin..xmax, view=[xmin..xmax,ymin..ymax]);

I was able to guess by trial and error that Maple selects something like -1.05 and 1.05 as the minimum and maximum values of the y-axis.

If I want to plot the positive quadrant only (for some reason), then I set the ymin and ymax as follows:

> ymin:=0: ymax:=1.05:

But  while I *know* that I want to select ymin:=0, I can only *guess* that I need ymax:=1.05. And if I change some parameters of my function that "optimal" ymax value may change as a result (while my ymin will not)

with Matlab I would have obtained the desired result by setting:

> ymin:=0: ymax:=inf:

Matlab *knows* that the appropriate value of ymax is 1.05 in this case, and automatically selects another value if I change the parameters of my function.

Thanks jakubi, so how about this?

> xmin:=-2*Pi: xmax:=2*Pi:
> p:= plot(cos(x), x=xmin..xmax):
> L2:=map(x->op(2,x),op([1,1],p)):
   ymax:=max(L2);
   ymin:=min(L2);

                     ymax := 0.99999999999999988


                     ymin := -0.99999928691950258

> L1:=map(x->op(1,x),op([1,1],p)):
   xmax:=max(L1);
   xmin:=min(L1);

                     xmax := 6.28318529460999998


                     xmin := -6.28318529460999998

it looks like the correct values in the example. I'll try to use that to create generic axes.

map(x->op(2,x),op([1,1],p)) remains esoteric to me even after looking up the map and op help, but it's growing on me! thanks!

so let's see how I can use this to achieve my underlying purpose.

purpose: in as little notation as possible, display a plot where the default axis has been overwritten by thicker lines (a workaround for the absence of control over axis thickness).

first attempt: I wrote a procedure (my first such) intended to do the above. It almost works. But not quite. The procedure is called "mydisplay" and is intended to replace the standard plots[display]

mydisplay := proc(p)
   local xy, xmin, xmax, ymin, ymax:
   local L1, L2:
   xmin:=-10: xmax:=10:
   L1:=map(x->op(1,x),op([1,1],p)): xmax:=max(L1): xmin:=min(L1):
   L2:=map(x->op(2,x),op([1,1],p)): ymax:=max(L2): ymin:=min(L2):
   xy := (xmin,xmax,ymin,ymax)-> 
   plots:-display(plottools[line]([xmin,0],[xmax,0],thickness=3), 
   plottools[line]([0,ymin],[0,ymax],thickness=3), 
   view=[xmin..xmax,ymin..ymax]):
   plots:-display({p,xy(xmin,xmax,ymin,ymax)},
   view=[xmin..xmax,ymin..ymax]):
   print(%):
 end proc:

Then, I can call the procedure:

p := plot(cos(x), x=-2*Pi..2*Pi):
mydisplay(p);

This sort of works (tested with Maple13/classic). If I want to control the x-axis, I can modify this part: plot(cos(x), x=-2..2): But it doesn't really work in that I have lost the ability to use the view=[-2..2,-0.5..0.5] option. So I need a procedure that can be used more like the standard call to display.

Is it possible to build a procedure that is a slightly modified version of an existing native Maple command?

EXACTLY what I was after, fantastic jakubi, thanks a lot.

I'm also learning how to build a procedure by studying your code.

thank you,

Patrick.