求解具有（wx）最大值的方程：控制堆栈已耗尽
我正在尝试使用（wx）Maxima求解方程：公式化公式，然后让其插入变量并为丢失的变量求解方程。但是我很难过。最后一行出现某种问题：
Control stack exhausted (no more space for function call frames).
This is probably due to heavily nested or infinitely recursive function
calls, or a tail call that SBCL cannot or has not optimized away.
这是我的代码：
kill(all);
load(physical_constants);
load(unit);
setunits([kg,m,s,N]);
showtime: false;
α: 30*%pi/180;
/*α: 30*°;*/
masse: 1000*kg;
g: 9.80665*m/(s*s);
b: 0.3*m;
B: 0.5*m;
L: 0.1*m;
F_g: masse*g;
F_H: masse * g;
kill(S, x);
S: solve(0=F_H-2*x*sin(α), x);
S: assoc(x, S);
kill(Ly, x);
Ly: solve(tan(α)=x/(B/2), x);
Ly: assoc(x, Ly);
kill(FN, x);
FN: solve(0=H*B/2-x*(L+Ly)+S*sin(α)*B/2+S*cos(α)*Ly, x);
FN: assoc(x, FN);
如果我直接“计算”，则可以：
kill(all);
load(physical_constants);
load(unit);
setunits([kg,m,s,N]);
showtime: false;
kill(FN, x);
FN: solve([α=30*%pi/180, H=196133/40*N,
B=0.5*m, L=0.1*m,
Ly=sqrt(3)/12*m, S=196133/20*N,
0=H*B/2-x*(L+Ly)+S*sin(α)*B/2+S*cos(α)*Ly],
[x, α, H, B, L, Ly, S]);
FN: assoc(x, FN[1]);
FN: float(FN);
(FN) 1934473685/128529*N
unit程序包有一段时间没有更新。我建议改用包ezunits，其中尺寸数量用反引号表示。要求解方程，请尝试dimensionally，它会经过一些回转，以帮助其他具有尺寸量的功能，例如dimensionally (solve (...))。 （请注意，dimensionally没有记录，对此缺点，我们深感抱歉。）我对您的程序进行了一些修改，以删除一些不需要的内容，并使用有理数代替浮点数； Maxima通常比有浮点数更适合使用有理数和整数。这是程序：
linel: 65 $
load(ezunits) $
α: 30*%pi/180;
masse: 1000`kg;
g: rationalize(9.80665)`m/(s*s);
b: 3/10`m;
B: 5/10`m;
L: 1/10`m;
F_g: masse*g;
F_H: masse * g;
S: dimensionally (solve(0=F_H-2*x*sin(α), x));
S: assoc(x, S);
Ly: dimensionally (solve(tan(α)=x/(B/2), x));
Ly: assoc(x, Ly);
FN: dimensionally (solve(0=H*B/2-x*(L+Ly)+S*sin(α)*B/2+S*cos(α)*Ly, x));
FN: assoc(x, FN);
subst (x = S, F_H-2*x*sin(α));
subst (x = Ly, tan(α)=x/(B/2));
subst (x = FN, H*B/2-x*(L+Ly)+S*sin(α)*B/2+S*cos(α)*Ly);
ratsimp (expand (%));
这是我得到的输出。请注意，我将解决方案代入方程式中进行验证。看起来像预期的那样工作。
(%i2) linel:65 (%i3) load(ezunits) (%i4) α:(30*%pi)/180 %pi (%o4) --- 6 (%i5) masse:1000 ` kg (%o5) 1000 ` kg (%i6) g:rationalize(9.80665) ` m/(s*s) 5520653160719109 m (%o6) ---------------- ` -- 562949953421312 2 s (%i7) b:3/10 ` m 3 (%o7) -- ` m 10 (%i8) B:5/10 ` m 1 (%o8) - ` m 2 (%i9) L:1/10 ` m 1 (%o9) -- ` m 10 (%i10) F_g:masse*g 690081645089888625 kg m (%o10) ------------------ ` ---- 70368744177664 2 s (%i11) F_H:masse*g 690081645089888625 kg m (%o11) ------------------ ` ---- 70368744177664 2 s (%i12) S:dimensionally(solve(0 = F_H-2*x*sin(α),x)) 690081645089888625 kg m (%o12) [x = ------------------ ` ----] 70368744177664 2 s (%i13) S:assoc(x,S) 690081645089888625 kg m (%o13) ------------------ ` ---- 70368744177664 2 s (%i14) Ly:dimensionally(solve(tan(α) = x/(B/2),x)) 1 (%o14) [x = --------- ` m] 4 sqrt(3) (%i15) Ly:assoc(x,Ly) 1 (%o15) --------- ` m 4 sqrt(3) (%i16) FN:dimensionally(solve(0 = (H*B)/2-x*(L+Ly) +(S*sin(α)*B)/2 +S*cos(α)*Ly,x)) 1 1 (%o16) [x = (----------------------------------------- ` --) 140737488355328 sqrt(3) + 351843720888320 2 s 2 (351843720888320 sqrt(3) H ` s 3/2 + 1150136075149814375 3 ` kg m)] (%i17) FN:assoc(x,FN) 1 1 (%o17) (----------------------------------------- ` --) 140737488355328 sqrt(3) + 351843720888320 2 s 2 (351843720888320 sqrt(3) H ` s 3/2 + 1150136075149814375 3 ` kg m) (%i18) subst(x = S,F_H-2*x*sin(α)) kg m (%o18) 0 ` ---- 2 s (%i19) subst(x = Ly,tan(α) = x/(B/2)) 1 1 (%o19) ------- = ------- sqrt(3) sqrt(3) (%i20) subst(x = FN,(H*B)/2-x*(L+Ly)+(S*sin(α)*B)/2+S*cos(α)*Ly) 1 1 (- ---------) - -- 4 sqrt(3) 10 1 (%o20) ((----------------------------------------- ` --) 140737488355328 sqrt(3) + 351843720888320 2 s 2 (351843720888320 sqrt(3) H ` s 3/2 H + 1150136075149814375 3 ` kg m) + -) ` m 4 2 690081645089888625 kg m + ------------------ ` ----- 281474976710656 2 s (%i21) ratsimp(expand(%)) 2 kg m (%o21) 0 ` ----- 2 s