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Annotation of OpenXM_contrib/pari/examples/taylor.gp, Revision 1.1

1.1     ! maekawa     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: }