matlab中怎么根据数据拟合分段函数（新手求助）

要拟合的是一个分段函数，这本身就不是一般的连续光滑函数。 nlinfit之所以要有初值这一项，就是考虑到在某些变态的情况下，无法找到最小二乘函数的最小值，可能是一个局部的最小值，也可能根本找不到，所以有必要通过改变迭代初值的方法进行试验。对于这种分段函数，最好的方法还是分段拟合。 fun1=inline('4.213-300*x/ref(1)-300*(ref(2)+ref(3))+300*ref(3)*exp(-x/(ref(3)*ref(4)))','ref','x'); fun2=inline('4.213-3000/ref(1)-300*ref(3)*exp(-x/(ref(3)*ref(4)))*(exp(10/(ref(3)*ref(4)))-1)','ref','x'); fun=@(ref,t)((t<=10).*fun1(ref,t)+(t>10).*fun2(ref,t)); t=0:0.1:50; v=[3.969 3.963 3.959 3.955 3.952 3.949 3.947 3.945 3.943 3.941 3.939 3.938 3.936 3.935 3.933 3.932 3.93 3.929 3.928 3.927 3.926 3.925 3.923 3.922 3.921 3.92 3.919 3.918 3.917 3.916 3.915 3.914 3.913 3.912 3.911 3.91 3.909 3.908 3.907 3.907 3.906 3.905 3.904 3.903 3.903 3.902 3.901 3.9 3.9 3.899 3.898 3.898 3.897 3.896 3.896 3.895 3.894 3.893 3.893 3.892 3.891 3.891 3.89 3.889 3.889 3.888 3.888 3.887 3.887 3.886 3.886 3.885 3.884 3.884 3.883 3.882 3.882 3.881 3.88 3.88 3.879 3.879 3.878 3.878 3.877 3.877 3.876 3.876 3.875 3.875 3.874 3.874 3.873 3.873 3.872 3.872 3.871 3.87 3.87 3.869 3.869 4.105 4.108 4.11 4.112 4.114 4.115 4.116 4.117 4.118 4.119 4.119 4.12 4.12 4.121 4.122 4.122 4.123 4.123 4.124 4.124 4.124 4.125 4.125 4.126 4.126 4.126 4.127 4.127 4.128 4.128 4.129 4.129 4.129 4.129 4.129 4.13 4.13 4.13 4.13 4.13 4.131 4.131 4.131 4.131 4.132 4.132 4.132 4.132 4.132 4.132 4.133 4.133 4.133 4.133 4.133 4.134 4.134 4.134 4.134 4.134 4.134 4.135 4.135 4.135 4.135 4.135 4.136 4.136 4.136 4.136 4.136 4.137 4.137 4.138 4.138 4.138 4.139 4.139 4.139 4.139 4.139 4.14 4.14 4.14 4.14 4.14 4.14 4.14 4.14 4.14 4.14 4.14 4.14 4.14 4.14 4.14 4.14 4.14 4.14 4.14 4.14 4.14 4.14 4.14 4.14 4.141 4.141 4.141 4.141 4.141 4.141 4.141 4.141 4.141 4.141 4.142 4.142 4.142 4.142 4.142 4.142 4.142 4.142 4.142 4.142 4.143 4.143 4.143 4.143 4.143 4.143 4.143 4.143 4.143 4.143 4.143 4.143 4.143 4.144 4.144 4.144 4.144 4.144 4.144 4.144 4.144 4.144 4.144 4.144 4.145 4.145 4.145 4.145 4.145 4.145 4.145 4.145 4.145 4.145 4.145 4.145 4.145 4.145 4.145 4.145 4.146 4.146 4.146 4.146 4.146 4.146 4.146 4.146 4.146 4.146 4.146 4.146 4.146 4.147 4.147 4.147 4.147 4.147 4.147 4.147 4.147 4.147 4.147 4.147 4.147 4.147 4.147 4.147 4.148 4.148 4.148 4.148 4.148 4.148 4.148 4.148 4.148 4.148 4.148 4.148 4.148 4.148 4.148 4.148 4.148 4.149 4.149 4.149 4.149 4.149 4.149 4.149 4.149 4.149 4.149 4.149 4.149 4.149 4.149 4.149 4.149 4.15 4.15 4.15 4.15 4.15 4.15 4.15 4.15 4.15 4.15 4.15 4.15 4.15 4.15 4.15 4.15 4.15 4.15 4.15 4.15 4.151 4.151 4.151 4.151 4.151 4.151 4.151 4.151 4.151 4.151 4.151 4.151 4.151 4.151 4.151 4.151 4.151 4.151 4.151 4.151 4.151 4.152 4.152 4.152 4.152 4.152 4.152 4.152 4.152 4.152 4.152 4.152 4.152 4.152 4.152 4.152 4.152 4.152 4.152 4.152 4.152 4.152 4.152 4.152 4.153 4.153 4.153 4.153 4.153 4.153 4.153 4.153 4.153 4.153 4.153 4.153 4.153 4.153 4.153 4.153 4.153 4.153 4.153 4.153 4.153 4.153 4.153 4.153 4.154 4.154 4.154 4.154 4.154 4.154 4.154 4.154 4.154 4.154 4.154 4.154 4.154 4.154 4.154 4.154 4.154 4.154 4.154 4.154 4.154 4.154 4.154 4.154 4.154 4.154 4.155 4.155 4.155 4.155 4.155 4.155 4.155 4.155 4.155 4.155 4.155 4.155 4.155 4.155 4.155 4.155 4.155 4.155 4.155 4.155 4.155 4.155 4.155 4.155 4.155 4.155 4.155 4.155 4.156 4.156 4.156 4.156 4.156 4.156 4.156 4.156 4.156 4.156 4.156 4.156 4.156 4.156 4.156 4.156 4.156 4.156 4.156 4.156 4.156 4.156 4.156 4.156 4.156 4.156 4.156 4.156 4.156 4.156 4.156 4.156]; abc=nlinfit(t',v,fun,[51891 0.00083 0.00013 12050]'); plot(t,v);hold on; f=@(t)(fun(abc,t)); fplot(f,[0,50],'r')