[NTG-context] Re: Metapost limitation ?

On 5/12/2024 3:57 PM, Fabrice Couvreur wrote:

Hi, When I want to draw the curve which corresponds to n=60 (blue curve), it doesn't seem possible: I don't understand. Thanks Fabrice

 \startMPpage[offset=1DK]

          numeric u;           u = 6cm;

          interim linejoin := mitered;           interim ahangle := 30;

          path xx, yy;           xx = ( (-0.3,0) -- 1.4 right) scaled u;           yy = ( (-0.1,0) -- 1.8 right) rotated 90 scaled u;

          def compute_curve(suffix f)(expr xmin, xmax, xinc) =               ((xmin,f(xmin))               for x=xmin+xinc step xinc until xmax:                    .. (x,f(x))               endfor)           enddef;

          for i = 1 upto 4:

          vardef f(expr x) =x+exp(-i*x) enddef;

          path curve;

          curve = compute_curve(f,-0.4,1.4,0.0001) scaled u;

          draw curve;

          endfor;

          vardef f(expr x) =x+exp(-6*x) enddef;

          path curve;

          curve = compute_curve(f,-0.4,1.4,0.0001) scaled u;

          draw curve;

          vardef f(expr x) =x+exp(-15*x) enddef;

          path curve;

          curve = compute_curve(f,-0.4,1.4,0.0001) scaled u;

          draw curve;

          vardef f(expr x) =x+exp(-60*x) enddef;

          path curve;

          curve = compute_curve(f,-0.4,1.4,0.0001) scaled u; ->>>>> not drawn

best put a comment before the ->>>>>>>

          draw curve withcolor blue;

          drawarrow (0,0) -- (u,0) withpen pencircle scaled 1.5bp;           drawarrow (0,0) -- (0,u) withpen pencircle scaled 1.5bp;

          label.urt("A",(0,1u));

          draw xx;           draw  yy;

          draw (1u,0) -- (1u,1.8u);

          label.llft("0",(0,0));

           vardef mark_y_axis(expr value, name) =             save p; pair p; p = value * u * up;             draw (left--right) scaled 1 shifted p;             label.lft(name, p shifted 2 left);           enddef;

          for a = 1 upto 1:             mark_y_axis(a, "");           endfor

           mark_y_axis(1, "$1$");

         vardef mark_x_axis(expr value, name) =            save p; pair p; p = value * u * right;            draw (up--down) scaled 1 shifted p;            label.bot(name, p shifted 2 down);          enddef;

         for a = 1 upto 1:            mark_x_axis(a, "");          endfor

         mark_x_axis(1, "$1$");

          path rectangle;           rectangle = (-0.3u,-0.4u) -- (1.3u,-0.4u) -- (1.3u,-0.4u) -- (1.3u,1.4u) -- (-0.3u,1.4u)--cycle;

          clip currentpicture to rectangle;          \stopMPpage

your exp usage: exp(-60*-0.4) if you see what huge numbers come out of that, like -51.006602 11100558579.857309 l -50.989594 11034154639.123087 l -50.972586 10968147929.149401 l -50.955579 10902536073.687559 l -50.938571 10837316710.703716 l you could imagine a viewer crapping out on that because no matter what one clips it still is 'kind of drawn', so what viewer do you use? Hans ----------------------------------------------------------------- Hans Hagen | PRAGMA ADE Ridderstraat 27 | 8061 GH Hasselt | The Netherlands tel: 038 477 53 69 | www.pragma-ade.nl | www.pragma-pod.nl -----------------------------------------------------------------