我编写了一个代码来评估蠕动泵送流速的临界值
dp = -(((theta - 1)+(1 + phi.*cos(2.*pi.*x))).*M.^3.*(cosh((1 + phi.*cos(2.*pi.*x)).*M)+ M.*beta.*sinh((1 + phi.*cos(2.*pi.*x)).*M)))./((1 + phi.*cos(2.*pi.*x)).*M.*cosh((1 + phi.*cos(2.*pi.*x)).*M)+(-1 +(1 + phi.*cos(2.*pi.*x)).*M.^2.*beta).*sinh((1 + phi.*cos(2.*pi.*x)).*M))-(alpha.*(M.^2.*((theta - 1)+(1 + phi.*cos(2.*pi.*x))).*(-1+2.*(1 + phi.*cos(2.*pi.*x)).^2.*M.^2+ cosh(2.*(1 + phi.*cos(2.*pi.*x)).*M)-2.*(1 + phi.*cos(2.*pi.*x)).*M.*sinh(2.*(1 + phi.*cos(2.*pi.*x)).*M)))./(8.*((1 + phi.*cos(2.*pi.*x)).*M.*cosh((1 + phi.*cos(2.*pi.*x)).*M)+(-1+(1 + phi.*cos(2.*pi.*x)).*M.^2.*beta).*sinh((1 + phi.*cos(2.*pi.*x)).*M)).^2));
和p = int(y,x,0,1 + phi.*cos(2.*pi.*x));
如果theta p = 0的临界值，theta的临界值是多少; 我写了代码：
M = 2;
alpha = 0.2;
beta = 0.03;
phi = 0.6;
theta = 0;
x = 0.5;
y = -(((theta - 1)+(1 + phi.*cos(2.*pi.*x))).*M.^3.*(cosh((1 + phi.*cos(2.*pi.*x)).*M)+ M.*beta.*sinh((1 + phi.*cos(2.*pi.*x)).*M)))./((1 + phi.*cos(2.*pi.*x)).*M.*cosh((1 + phi.*cos(2.*pi.*x)).*M)+(-1 +(1 + phi.*cos(2.*pi.*x)).*M.^2.*beta).*sinh((1 + phi.*cos(2.*pi.*x)).*M))-(alpha.*(M.^2.*((theta - 1)+(1 + phi.*cos(2.*pi.*x))).*(-1+2.*(1 + phi.*cos(2.*pi.*x)).^2.*M.^2+ cosh(2.*(1 + phi.*cos(2.*pi.*x)).*M)-2.*(1 + phi.*cos(2.*pi.*x)).*M.*sinh(2.*(1 + phi.*cos(2.*pi.*x)).*M)))./(8.*((1 + phi.*cos(2.*pi.*x)).*M.*cosh((1 + phi.*cos(2.*pi.*x)).*M)+(-1+(1 + phi.*cos(2.*pi.*x)).*M.^2.*beta).*sinh((1 + phi.*cos(2.*pi.*x)).*M)).^2));
p = int(y,x,0,1 + phi.*cos(2.*pi.*x));
sym theta
solve( 'p','theta' );
检查一点，但我得到了
Undefined function or method 'int' for input arguments of type 'double'.