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Annotation of OpenXM_contrib/pari-2.2/examples/taylor.gp, Revision 1.1.1.1

1.1       noro        1: \\ originally contributed by Ilya Zakharevich
                      2:
                      3: \\ sample function
                      4: f(x) = sin(x)
                      5:
                      6: \\ plot Taylor polynomials of f of index first + i*step <= ordlim
                      7: \\ for x in [xmin,xmax].
                      8: plot_taylor(xmin=-5, xmax=5, ordlim=16, first=1, step=1) =
                      9: {
                     10:   local(T,Taylor_array,s,t,w,h,dw,dh,cw,ch,gh,h1, extrasize = 0.6);
                     11:
                     12:   default(seriesprecision,ordlim+1);
                     13:   ordlim -= first; ordlim \= step; ordlim += first;
                     14:   T = f(tt); Taylor_array = vector(ordlim+1);
                     15:   forstep(i=ordlim+1, 1, -1,
                     16:     T += O(tt^(1 + first + (i-1)*step));
                     17:     Taylor_array[i] = truncate(T)
                     18:   );
                     19:
                     20:   t = plothsizes();
                     21:   w=floor(t[1]*0.9)-2; dw=floor(t[1]*0.05)+1; cw=t[5];
                     22:   h=floor(t[2]*0.9)-2; dh=floor(t[2]*0.05)+1; ch=t[6];
                     23:   h1=floor(h/1.2);
                     24:
                     25:   plotinit(2, w+2*dw, h+2*dh);
                     26:   plotinit(3, w, h1);
                     27:   s = plotrecth(3, x=xmin,xmax, f(x), 2+8+16+32);
                     28:   gh=s[4]-s[3];
                     29:
                     30:   plotinit(3, w, h);
                     31:   plotscale(3,s[1],s[2],s[3]-gh*extrasize/2,s[4]+gh*extrasize/2);
                     32:   plotrecth(3, x=xmin,xmax,
                     33:     concat(f(x), subst(Taylor_array, tt, x)), 4);
                     34:   plotclip(3);
                     35:   plotcopy(3, 2, dw, dh);
                     36:
                     37:   plotmove(2,floor(dw+w/2-15*cw),floor(dh/2));
                     38:   plotstring(2,"Multiple Taylor Approximations");
                     39:   plotdraw([2, 0, 0])
                     40: }