请教---Hspice的RUNLVL=5 与6精度差多少？
Hspice中.OPTION RUNLVL=5 比 RUNLVL=6的仿真速度快好几倍，但是，不知道精度损失大不大?
没有精度差别，runlvl只是系统程序优先级，精度是由option选项设置的。
同问，看hspice手册中关于runlvl的设置，1到6精度依次变高，runlvl=0是关闭了这一选项功能，那0和6的精度是哪个高呢?
When .OPTION RUNLVL=0 is set, HSPICE uses thetraditional control option
values. These values aim for superior accuracy
往后翻了翻，0是精度最高的
RUNLVL = x
Controls the speed and accuracy trade-off.
It canbe set to 0,1,2,3,4,5,6. Higher values of RUNLVL result in higher accuracy and longer simulation times, while lower values give lower accuracy and faster simulation runtimes.
RUNLVL=0 turns off this algorithm.
RUNLVL=1 is the lowest simulation runtime.
RUNLVL=3 is the default (similar to original HSPICE default mode).
RUNLVL=5, 6 correspond to the HSPICE standard accurate mode.
For most circuits, RUNLVL=5 is similar to the HSPICE standard
accurate mode.
RUNLVL = x Controls the speed and accuracy trade-off. It can
be set to 0,1,2,3,4,5,6. Higher values of RUNLVL
result in higher accuracy and longer simulation
times, while lower values give lower accuracy and
faster simulation runtimes.
RUNLVL=0 turns off this algorithm.
RUNLVL=1 is the lowest simulation runtime.
RUNLVL=3 is the default (similar to original
HSPICE default mode).
RUNLVL=5, 6 correspond to the HSPICE
standard accurate mode. For most circuits,
RUNLVL=5 is similar to the HSPICE standard
accurate mode.
1-3 for digital circuit 
有辦法 中間 改變 runlvl 嗎
前面如果須要很長 ramp up time ..
是否可以前面降低 accuracy
後面再拉高 ?