编了一个材积计算的程序，但结果果有偏差，4M，20CM的材种是0.16，计算得出是0.152。请帮一帮。
源代码如下 ：
local ll as numeric  ,dd as numeric,nn as numeric,v1 as numeric,vv11 as numeric,vv1 as numeric,vv as numeric,cai as numeric
SET DECIMALS TO 4
SET FIXED ON     

ll=thisform.text1.value
 dd=thisform.text2.value
 nn=thisform.text3.value
 IF ll<10.1
   IF dd>12
       vv1=1000*0.000125*ll*(14-ll)*(14-ll)*(dd-10)
       vv11=round(vv1,3)
       v1=dd+0.5*ll+0.005*ll*ll+vv11/1000
       vv=7854*ll*v1*v1/100000000
       cai=nn*(int(vv*1000+0.5))/1000
      
       thisform.text4.value  =cai      
   ELSE
     IF dd>7
       v1=dd+0.45*ll+0.2
       vv=0.7854*ll*v1*v1/10000
       cai=nn*(int(vv*1000+0.5))/1000
       thisform.text4.value  =cai      
     ENDIF
   ENDIF
    v1=dd+0.45*ll+0.2
    vv=0.7854*ll*v1*v1/10000
 ELSE
    IF dd>7
      v1=dd+0.5*ll
      vv=0.8*ll*v1*v1/10000
      cai=nn*(int(vv*1000+0.5))/1000
      thisform.text4.value  =cai      
    ELSE
      v1=dd+0.5*ll
      vv=0.8*ll*v1*v1/10000
    ENDIF
ENDIF
cai=nn*(int(vv*10000+0.5))/10000
thisform.text4.value  =cai      

象这种多选项的分支用case语句更简洁，程序执行效率也更高。
语句中许多int()函数，建议全部取消，并将倒数第二行改为：
cai=round(nn*vv,4)
这样计算的精度肯定会提高

楼上，您好，我改了后，计算精度还是一样，没有变化。请指教!

计算的结果是：0.1521，这是用每一个分支计算的，别的分支计算都对，应该是个编程技巧问题。请大师指教!

改成下面的试试看能否达到要求。
local ll as numeric  ,dd as numeric,nn as numeric,v1 as numeric,vv11 as numeric,vv1 as numeric,vv as numeric,cai as numeric
SET DECIMALS TO 4
SET FIXED ON     

ll=thisform.text1.value
dd=thisform.text2.value
nn=thisform.text3.value
IF ll<10.1
   IF dd>12
       vv1=1000*0.000125*ll*(14-ll)*(14-ll)*(dd-10)
       v1=dd+0.5*ll+0.005*ll*ll+vv1/1000
   ELSE
     IF dd>7
       v1=dd+0.45*ll+0.2
     ENDIF
   ENDIF
   vv=0.7854*ll*v1*v1/10000
ELSE
    IF dd>7
      v1=dd+0.5*ll
      vv=0.8*ll*v1*v1/10000
    ELSE
      v1=dd+0.5*ll
      vv=0.8*ll*v1*v1/10000
    ENDIF
ENDIF
cai=round(nn*vv,4)
thisform.text4.value  =cai