小弟初学MATLAB没几天,编了个算权证的公式,可是出现问题,出了inf,计算无法继续.请高手指点,见笑了.

function p = bs(r,t,sigma,s,x)

% This function calculates the value of

% Define varibales

% r--无风险利率 连续复利 单位：年

% t--权证到期时间

% sigma--标的股票波动率

% s--标的股票现价

% x--权证规定的执行价格

r = input('Enter the value of r: ');

t = input('Enter the valur of t: ');

sigma = input('Enter the value of sigma: ');

s = input('Enter the value of s: ');

x = input('Enter the value of x: ');

d1 = (log(s/x)+(r+sigma^2/2)*t)/sigma*sqrt(t)

d2= d1-sigma*sqrt(t)

p=x*exp(-r*t)*normcdf(-d2,0,1)-s*normcdf(-d1,0,1)

??? Input must be real.

Error in ==> erfc at 21

y = erfcore(x,1);

Error in ==> normcdf at 68

p = 0.5 * erfc(-z ./ sqrt(2));

Error in ==> bs at 16

p=x*exp(-r*t)*normcdf(-d2,0,1)-s*normcdf(-d1,0,1)