Trying to solve a definite integral but wont give numerical solution

1 次查看（过去 30 天）
Heather Holzer
Heather Holzer 2019-8-23
评论： Heather Holzer 2019-8-23
  1. Q=150;
  2. k=1.49;
  3. n=0.02;
  4. So=0.0048;
  5. b=3;
  6. g=32.2;
  7. x1=0;
  8. y1=3; %x2=200;
  9. h=20;
  10. x2=200;
  11. syms y;
  12. f_xy=(So-((Q*n)/(k*b*(y^(5/3))))^2)/(1-((Q^2)/((b^2)*g*y^3)));
  13. func=int(f_xy,y,[x1 x2]);
  14. vfunc=vpa(func);
  15. y=y1+vfunc;
  16. ys=string(y);
  17. yf=str2double(ys);
this is what shows up in the varaibles for ys= "int((10000/(22201*y^(10/3)) - 3/625)/(12500/(161*y^3) - 1), y, 0, 200) + 3"
Also the above equation is not how it should look with variables plugged in.

请先登录，再回答此问题。

采纳的回答

Torsten
Torsten 2019-8-23
Q=150;
k=1.49;
n=0.02;
So=0.0048;
b=3;
g=32.2;
x1=0;
y1=3; %x2=200;
h=20;
x2=200;
f_xy=@(y)(So-((Q*n)./(k*b*(y.^(5/3)))).^2)./(1-((Q^2)./((b^2)*g*y.^3)));
vfunc=integral(f_xy,x1,x2);
y=y1+vfunc
  7 个评论
显示 5更早的评论
Torsten
Torsten 2019-8-23
编辑：Torsten 2019-8-23
Q=150;
k=1.49;
n=0.02;
So=0.0048;
b=3;
g=32.2;
x1=0;
y1=3; %x2=200;
h=20;
x2=[20,40,60];
f_xy=@(y)(So-((Q*n)./(k*b*(y.^(5/3)))).^2)./(1-((Q^2)./((b^2)*g*y.^3)));
vfunc = zeros(numel(x2,1));
for i=1:numel(x2)
vfunc(i) = integral(f_xy,x1,x2(i));
end
y = y1+vfunc
But - as already said - you should check whether the integral exists at all.

请先登录，再进行评论。

更多回答（0 个）

类别

在 Help Center 和 File Exchange 中查找有关 Symbolic Math Toolbox 的更多信息

标签

产品


版本

R2018b

Community Treasure Hunt

Find the treasures in MATLAB Central and discover how the community can help you!

Start Hunting!

Translated by