B[w_, q_, a_, qs_, qm_, r_, c_] :=
w q + (a - (q - qs + qm) - r qs - c) qm
B3[w_, a_, r_, c_] :=
B[w, (2 (a (11 + 4 r + r^2) + c (7 + 8 r + r^2) -
2 (3 + r)^2 (1 + t) w))/(23 + 31 r + 9 r^2 + r^3), a,
1/4 (2 (2 (a (11 + 4 r + r^2) + c (7 + 8 r + r^2) -
2 (3 + r)^2 (1 + t) w))/(23 + 31 r + 9 r^2 + r^3) + (
2 a - 2 c - (
2 (a (11 + 4 r + r^2) + c (7 + 8 r + r^2) -
2 (3 + r)^2 (1 + t) w))/(
23 + 31 r + 9 r^2 + r^3) - (
2 (a (11 + 4 r + r^2) + c (7 + 8 r + r^2) -
2 (3 + r)^2 (1 + t) w))/(23 + 31 r + 9 r^2 + r^3) r)/(
3 + r)), (
2 a - 2 c - (
2 (a (11 + 4 r + r^2) + c (7 + 8 r + r^2) -
2 (3 + r)^2 (1 + t) w))/(
23 + 31 r + 9 r^2 + r^3) - (
2 (a (11 + 4 r + r^2) + c (7 + 8 r + r^2) -
2 (3 + r)^2 (1 + t) w))/(23 + 31 r + 9 r^2 + r^3) r)/(3 + r),
r, c]
D[B3[w, a, r, c], w]
第二步（B3函数那一步）是对变量进行赋值，赋值是之前计算的结果，因为不会用matlab中的sub函数，就直接复制粘贴来赋值了
想问问为什么算出来的结果会有标红的那一部分，谢谢啦
