matlab绘图求助 提示错误Conversion to double from sym is not possible

matlab绘图求助 提示错误Conversion to double from sym is not possible.
想绘如下的图
syms t r
h=0.000013118/r*(cosh(9.8^((1/2)*t))-1)
[t,r]=meshgrid(0:1:100,0.01:0.0001:0.001)
plot3(t,r,h)
但是提示：
? Error using ==> plot3
Conversion to double from sym is not possible.
我是新手
实在不懂怎么弄

clear;clc;
A=[...
1 15 15 18.4
2 550 15 16.8
3 1085 15 17.4
4 145 170 16.8
5 415 170 18.2
6 685 170 18.2
7 955 170 16.2
8 280 330 19.3
9 820 330 17.4
10 145 490 16.8
11 415 490 19.4
12 685 490 18.9
13 955 490 16.3
14 15 650 17.5
15 550 650 19.3
16 1085 650 17.0
17 145 810 16.7
18 415 810 19.2
19 685 810 19.3
20 955 810 17.0
21 280 970 17.4
22 820 970 19.0
23 145 1130 15.9
24 415 1130 18.2
25 685 1130 17.8
26 955 1130 16.5
27 15 1285 17.5
28 550 1285 16.8
29 1085 1285 17.3];
x=A(:,2);y=A(:,3);z=A(:,4);
xi=min(x):20:max(x);yi=min(y):20:max(y);
[X,Y]=meshgrid(xi,yi);
Z=griddata(x,y,z,X,Y,'cubic');
mesh(X,Y,Z);
xlabel('x'),ylabel('y'),zlabel('RS')
图形见：
另一组数据大同小异：
clear;clc;
A=[...
15 15 27.49
15 330 27.49
15 650 27.28
15 970 27.39
15 1285 27.52
145 1130 27.46
145 810 27.29
145 490 27.46
145 170 27.44
280 15 27.36
280 330 27.50
280 650 27.30
280 970 27.31
280 1285 27.52
415 1130 27.35
415 810 27.27
415 490 27.44
415 170 27.27
550 15 27.25
550 330 27.33
550 650 27.25
550 970 27.36
550 1285 27.41
685 1130 27.38
685 810 27.30
685 490 27.25
685 170 27.25
820 15 27.46
820 330 27.32
820 650 27.39
820 970 27.32
820 1285 27.61
955 1130 27.42
955 810 27.34
955 490 27.30
955 170 27.35
1085 15 27.46
1085 330 27.28
1085 650 27.41
1085 970 27.47
1085 1285 27.72 ];
x=A(:,1);y=A(:,2);z=A(:,3);
xi=min(x):20:max(x);yi=min(y):20:max(y);
[X,Y]=meshgrid(xi,yi);
Z=griddata(x,y,z,X,Y,'cubic');
mesh(X,Y,Z);
xlabel('x'),ylabel('y'),zlabel('RS')