我有下面的代码,它的工作很好,直到第二次到最后一次指令。
(%i17) M_A;
(%o17) [500.0,-0.22*F_Bz-750.0,0.22*F_By-105.0]
(%i18) solve(M_A[2]);
rat: replaced -750.0 by -750/1 = -750.0
rat: replaced -0.22 by -11/50 = -0.22
(%o18) [F_Bz=-37500/11]
(%i19) solve(M_A[3]);
rat: replaced -105.0 by -105/1 = -105.0
rat: replaced 0.22 by 11/50 = 0.22
(%o19) [F_By=5250/11]
(%i20) F_Br : sqrt(F_By^2+F_Bz^2);
(%o20) sqrt(F_Bz^2+F_By^2)
(%i21) float(%);
(%o21) sqrt(F_Bz^2+F_By^2)如何才能得到%i20的数字答案。

发布于 2021-10-31 00:53:33
下面是我尝试将方程的解替换为F_Br表达式时得到的结果。见%i7和%o7。
(%i3) M_A:[500.0,(-0.22)*F_Bz-750.0,0.22*F_By-105.0]
(%o3) [500.0, (- 0.22 F_Bz) - 750.0, 0.22 F_By - 105.0]
(%i4) s1:solve(M_A[2])
rat: replaced -750.0 by -750/1 = -750.0
rat: replaced -0.22 by -11/50 = -0.22
37500
(%o4) [F_Bz = - -----]
11
(%i5) s2:solve(M_A[3])
rat: replaced -105.0 by -105/1 = -105.0
rat: replaced 0.22 by 11/50 = 0.22
5250
(%o5) [F_By = ----]
11
(%i6) F_Br:sqrt(F_By^2+F_Bz^2)
2 2
(%o6) sqrt(F_Bz + F_By )
(%i7) subst(append(s1,s2),F_Br)
750 sqrt(2549)
(%o7) --------------
11
(%i8) float(%)
(%o8) 3442.337880372093https://stackoverflow.com/questions/69770313
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