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: }
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