fplot in Matlab error
5 ビュー (過去 30 日間)
古いコメントを表示
% I am trying to plot these three eqyations but evrytime I hit run this error shows "Error using fplot (line 149)
Invalid parameter ' ...'."
clear all;
syms V(t) a b C
time = [3.46
4.58
5.67
6.64
7.63
8.41
9.32
10.27
11.19
12.39
13.42
15.19
16.24
17.23
18.18
19.29
21.23
21.99
24.33
25.58
26.43
27.44
28.43
30.49
31.34
32.34
33
35.2
36.34
37.29
38.5
39.67
41.37
42.58
45.39
46.38
48.29
49.24
50.19
51.14
52.1
54
56.33
57.33
59.38];
Voltage = [0.0158
0.0264
0.0326
0.0445
0.0646
0.0933
0.1454
0.2183
0.2842
0.4977
0.6033
0.8441
1.2163
1.447
2.3298
2.5342
3.0064
3.4044
3.2046
4.5241
4.3459
5.1374
5.5376
4.8946
5.066
6.1494
6.8548
5.9668
6.6945
6.6395
6.8971
7.2966
7.2268
6.8815
8.0993
7.2112
7.0694
7.4971
6.9974
6.7219
7.0523
7.1095
7.0694
8.0562
7.2268];
a = 0.3389;
b = 0.0489;
sol1 = (a*tanh((a*(C+t))/2)+1)/(2*b)
a = 0.4340;
b = 0.2158;
sol2 = ((a./b).*C.*exp(a.*t))./((a./b)+C.*exp(a.*(t-1)))
syms V(t) a b C
cond = [V(0) == C]
a = 0.2375;
b = 0.1179;
eq = diff(V) == a*V-b*V*log(V);
sol3 = dsolve(eq, cond)
fplot(sol1,time,'ro')
hold on
plot(time,sol2,'B')
plot(time, sol3,'G')
hold off
legend('Data', 'Gompertz', 'Bertalanffy', 'logistic');
title(' three models')
xlabel('Time (days)');
ylabel('Voltage');
0 件のコメント
回答 (1 件)
Star Strider
2020 年 11 月 9 日
Note that ‘sol1’ is a function of both ‘C’ and ‘t’. Since ‘C’ is undefined, fplot throws the error. One option is to use another function, and provide a range of values for ‘C’:
fsurf(sol1,[min(Voltage) max(Voltage) min(time) max(time)])
The arguments are taken in lexical order, so here ‘C’ is assigned ‘Voltage’ and ‘t’ is assigned ‘time’.
2 件のコメント
Star Strider
2020 年 11 月 9 日
Not necessarily.
I have no idea what your equations are modeling, so I cannot suggest an approach. I would keep them as they are (at least ‘sol1’ as a function only of time), and define ‘C’ as some numeric scalar constant before you calculate ‘sol1’. The fplot function requires that the functions it is given are functions of only one variable.
I leave that to you to decide how you want to approach that.
Also, note that:
sol1 = @(t) ((a*tanh((a*(Voltage+time))/2)+1)/(2*b))
is not actually a function of ‘t’. I would just leave it the way it is in the code you posted, and define ‘C’ as a numeric scalar.
参考
カテゴリ
Help Center および File Exchange で Calculus についてさらに検索
Community Treasure Hunt
Find the treasures in MATLAB Central and discover how the community can help you!
Start Hunting!