1楼：匿名用户
题主给出微分方程组，可使用ss创建广义状态空间（gesss）模型，即将动态系统模型转换为状态空间模型形式。其模型
按照ss的方法，可以这样求解（供参考）。
a=[0,1,0;0,0,1;-2,-4,-3];
b=[1,0;0,1;-1,0];
c=[0,1,0;1,2,1];
d=[0];
x0=[1;0;0];
sys=ss(a,b,c,d);
[y,t,x] =initial(sys,x0,t);
plot(t,x,'.-',t,y,'p')运行结果
matlab状态方程解
2楼：化学工程
有关热力学的吗？还是别的？
哦！解析法是不行，那就用数值方法吧。
function odemethod
[t,x]=ode23t(@fun,0:0.1:10,[0 0 0 0])
plot(t,x)
legend('x','y','z','t'),xlabel('t')
function dx=fun(t,x)
x=x(1);y=x(2);z=x(3);w=x(4);
dx1=-0.0558*x-0.9968*y+0.0802*z+0.0415*w+0.00729;
dx2=0.598*x-0.115*y-0.0318*z-0.475+0.00775;
dx3=-0.05*x+0.388*y-0.465*z+0.296;
dx4=0.805*x+z;
dx=[dx1;dx2;dx3;dx4];
运行结果：
t =0
0.1000
0.2000
0.3000
0.4000
0.5000
0.6000
0.7000
0.8000
0.9000
1.0000
1.1000
1.2000
1.3000
1.4000
1.5000
1.6000
1.7000
1.8000
1.9000
2.0000
2.1000
2.2000
2.3000
2.4000
2.5000
2.6000
2.7000
2.8000
2.9000
3.0000
3.1000
3.2000
3.3000
3.4000
3.5000
3.6000
3.7000
3.8000
3.9000
4.0000
4.1000
4.2000
4.3000
4.4000
4.5000
4.6000
4.7000
4.8000
4.9000
5.0000
5.1000
5.2000
5.3000
5.4000
5.5000
5.6000
5.7000
5.8000
5.9000
6.0000
6.1000
6.2000
6.3000
6.4000
6.5000
6.6000
6.7000
6.8000
6.9000
7.0000
7.1000
7.2000
7.3000
7.4000
7.5000
7.6000
7.7000
7.8000
7.9000
8.0000
8.1000
8.2000
8.3000
8.4000
8.5000
8.6000
8.7000
8.8000
8.9000
9.0000
9.1000
9.2000
9.3000
9.4000
9.5000
9.6000
9.7000
9.8000
9.9000
10.0000
x =0 0 0 0
0.0032 -0.0464 0.0280 0.0015
0.0111 -0.0921 0.0530 0.0061
0.0237 -0.1367 0.0751 0.0139
0.0408 -0.1799 0.0945 0.0250
0.0622 -0.2216 0.1112 0.0394
0.0877 -0.2614 0.1256 0.0573
0.1172 -0.2992 0.1377 0.0787
0.1502 -0.3347 0.1477 0.1038
0.1868 -0.3678 0.1558 0.1325
0.2264 -0.3983 0.1621 0.1650
0.2689 -0.4260 0.1668 0.2014
0.3139 -0.4508 0.1701 0.2417
0.3612 -0.4725 0.1722 0.2860
0.4104 -0.4912 0.1732 0.3344
0.4613 -0.5066 0.1732 0.3868
0.5135 -0.5189 0.1724 0.4433
0.5667 -0.5278 0.1711 0.5039
0.6206 -0.5335 0.1692 0.5687
0.6748 -0.5359 0.1670 0.6377
0.7291 -0.5350 0.1646 0.7108
0.7831 -0.5309 0.1622 0.7880
0.8366 -0.5237 0.1598 0.8693
0.8892 -0.5133 0.1576 0.9546
0.9407 -0.5000 0.1557 1.0439
0.9908 -0.4838 0.1542 1.1371
1.0393 -0.4649 0.1532 1.2342
1.0859 -0.4434 0.1527 1.3350
1.1304 -0.4194 0.1530 1.4395
1.1726 -0.3931 0.1539 1.5475
1.2123 -0.3647 0.1557 1.6589
1.2493 -0.3344 0.1583 1.7737
1.2836 -0.3022 0.1618 1.8916
1.3149 -0.2685 0.1662 2.0126
1.3432 -0.2335 0.1715 2.1364
1.3683 -0.1973 0.1779 2.2630
1.3903 -0.1601 0.1852 2.3922
1.4090 -0.1221 0.1935 2.5237
1.4244 -0.0836 0.2028 2.6576
1.4365 -0.0447 0.2131 2.7935
1.4453 -0.0057 0.2244 2.9314
1.4509 0.0333 0.2365 3.0710
1.4533 0.0720 0.2496 3.2122
1.4525 0.1103 0.2636 3.3548
1.4487 0.1480 0.2783 3.4987
1.4419 0.1848 0.2938 3.6436
1.4322 0.2207 0.3101 3.7895
1.4199 0.2555 0.3270 3.9361
1.4049 0.2890 0.3444 4.0833
1.3876 0.3211 0.3625 4.2310
1.3680 0.3517 0.3809 4.3791
1.3463 0.3807 0.3998 4.5273
1.3227 0.4079 0.4189 4.6757
1.2974 0.4333 0.4383 4.8239
1.2706 0.4568 0.4579 4.9721
1.2425 0.4783 0.4776 5.1200
1.2133 0.4978 0.4973 5.2676
1.1832 0.5153 0.5170 5.4147
1.1525 0.5307 0.5364 5.5613
1.1211 0.5441 0.5558 5.7074
1.0895 0.5553 0.5749 5.8529
1.0579 0.5645 0.5936 5.9977
1.0263 0.5717 0.6120 6.1419
0.9951 0.5769 0.6299 6.2853
0.9643 0.5801 0.6473 6.4280
0.9342 0.5814 0.6642 6.5700
0.9049 0.5809 0.6804 6.7113
0.8767 0.5787 0.6960 6.8518
0.8495 0.5747 0.7110 6.9917
0.8237 0.5693 0.7252 7.1308
0.7994 0.5623 0.7386 7.2694
0.7766 0.5540 0.7513 7.4074
0.7554 0.5444 0.7631 7.5448
0.7361 0.5338 0.7742 7.6817
0.7186 0.5220 0.7844 7.8182
0.7031 0.5095 0.7937 7.9544
0.6895 0.4962 0.8023 8.0903
0.6780 0.4822 0.8099 8.2260
0.6686 0.4678 0.8168 8.3616
0.6613 0.4531 0.8228 8.4972
0.6561 0.4380 0.8280 8.6328
0.6530 0.4229 0.8325 8.7686
0.6520 0.4079 0.8362 8.9047
0.6531 0.3930 0.8391 9.0410
0.6563 0.3784 0.8413 9.1778
0.6614 0.3642 0.8429 9.3151
0.6685 0.3504 0.8438 9.4529
0.6774 0.3374 0.8442 9.5916
0.6882 0.3250 0.8440 9.7310
0.7006 0.3135 0.8433 9.8713
0.7147 0.3029 0.8422 10.0126
0.7302 0.2933 0.8406 10.1549
0.7471 0.2848 0.8387 10.2983
0.7653 0.2774 0.8365 10.4430
0.7847 0.2712 0.8341 10.5889
0.8050 0.2663 0.8314 10.7362
0.8263 0.2627 0.8286 10.8849
0.8484 0.2604 0.8257 11.0351
0.8711 0.2595 0.8228 11.1867
0.8942 0.2600 0.8199 11.3399
0.9178 0.2618 0.8171 11.4947