[通用算法] 负数求三次方根的NaN问题，多谢啦！

program ex110
implicit none
DIMENSION U(2),UI1(3),UI2(6),UI3(6) 
REAL(8) Nv, chi, lambda0, detF0,vcho,vcmo,vcpo,fa,fb,Ka,Kb,vNa
REAL(8) U ,UI1, UI2 ,UI3,aa, bb, cc ,dd, ee, deltaa, deltab,deltac
REAL(8) BI1,BI2,AJ
REAL(8) delta,vch,GAJ, DGAJDAJ, DDGAJDDAJ, DDDGAJDDDAJ 
REAL(8) DGAJDvch ,DDGAJDDvch, DDDGAJDDDvch 
REAL(8) DDGAJDAJDvch, DDDGAJDAJDDvch, DDDGAJDDAJDvch
REAL(8) DvchDAJ, DDvchDDAJ, DDDvchDDDAJ
REAL(8) D1GAJDAJ, D2GAJDAJ, D3GAJDAJ,TEMP
BI1=10.0
AJ=1.0
TEMP=2.0
Nv = 0.001
chi = 0.1
lambda0 = 3.39
detF0 = lambda0**3.0
vNa=0.0602
vcpo=vNa*(10.0**(-3.0))
vcho=vNa*(10.0**(-TEMP))
vcmo=vcpo+vcho
Ka=10.0**(-4.3)
Kb=10.0**(-10.0)
fa=0.05
fb=0.0
!。。。。。。中间省略部分无关代码


aa=AJ*detF0*(vcho+vcpo)

bb=fb*vcho+AJ*detF0*Ka*(vcho+vcpo)*vNa+ AJ*detF0*Kb*(vcho + 
&vcpo)*vNa

cc=-(AJ*detF0*vcho**2*vcmo)-fa*Ka*vcho*vNa+fb*Ka*vcho*vNa+ 
&AJ*detF0*Ka*Kb*(vcho+vcpo)*vNa**2
dd=-(AJ*detF0*Ka*vcho**2*vcmo*vNa)-AJ*detF0*Kb*vcho**2*vcmo*v
&Na-fa*Ka*Kb*vcho*vNa**2

ee=AJ*detF0*Ka*Kb*vcho**2*vcmo*vNa**2

deltaa=cc**2-3*bb*dd+12*aa*ee

deltab=2*cc**3-9*bb*cc*dd+27*aa*dd**2-72*aa*cc*ee
deltac=(deltab+Sqrt(abs(-4.0*deltaa**3.0+deltab**2.0)))
&**(1.0/3.0)

delta=(2**(1/3)*deltaa)/(3*aa*deltac)+deltac/(3*2**(1/3)*aa)
!。。。。。。。。。。。以下省略部分无关代码。。。。。。。。。

Program www_fcode_cn
  Implicit None
  real(8) :: d = -1.63899782385934d-24 , s
  s = sign(1.0d0,d)*abs(d)**(1.0d0/3.0d0)
  write(*,*) s , d , s*s*s
End Program www_fcode_cn

integer n
write(*,*) "有100个苹果分给小朋友，"
write(*,*) "请输入小朋友的个数"
read(*,*) n
write(*,*) "每个小朋友获得" , 100/n , "个苹果"
end