呃,一个简单的笔误而已...
data = {{0,0},{0.115,0.11},{0.173,0.14},{0.231,0.24},{0.346,
0.29},{0.461,0.31},{0.5,0.32}};
model = D^2/(D^2 + (0.7 D + 2416.4)^2)*(Sin[
0.5*x*Sqrt[D*D + (0.84 D + 2899.7)^2]])^2;
fit = FindFit[data,{model,{D >= 0}},{D},x]
注意仅仅是把model的表达式的一组[]改成了().
运行前三行代码,结果为
{D -> 1.03161}
其实错误提示已经说得比较明显了,