关于曲线拟和和微分方程的问题

wolfnet

我用CFtool对2组数据进行拟和,得到的方程如下
y=-0.002:0.00001:0.002;
i=(0.0006455*exp(0.4182*(10*y/0.001+21)) + (-3.971e+004)*exp(-0.4854*(10*y/0.001+21)))*0.1/100;
这里有个问题,如果我设置y是自变量或者y是-0.002:0.002的话,出来的结果就完全不同.
这样的话就导致了后面我用ode45对dy /dt=240sin(100*pi*t)-i这个方程计算出错.有什么方法可以解决呢?

原始数据如下:
Bdata=[-2.0,-1.95,-1.9,-1.8,-1.7,-1.6,-1.5,-1.4,-1.3,-1.2,-1.1,-1.0,-0.9,-0.8,-0.7,-0.6,-0.5,-0.4,-0.3,-0.2,-0.1,0,0.1,0.2,0.3,0.4,0.5,0.6,0.7,0.8,0.9,1.0,1.1,1.2,1.3,1.4,1.5,1.6,1.7,1.8,1.9,1.95,2.0];
Hdata=[-40000,-27000,-21000,-14000,-9100,-5300,-2650,-1100,-420,-240,-160,-125,-112.5,-100,-87.5,-75,-62.5,-50,-37.5,-25,-12.5,0,12.5,25,37.5,50,62.5,75,87.5,100,112.5,125,160,240,420,1100,2650,5300,9100,14000,21000,27000,40000]
y=Bdata*0.001

[ 本帖最后由 wolfnet 于 2008-11-17 02:46 编辑 ]