wavelengthfind1.m

通过配置参数来计算导入的LPFG（.xls格式data）的中心波长

format long
format compact
p=16;
q=162;s=836;
Lengthaq=[];
coll=11;
for n=2:coll
       i=q;j=2;
while (i<s) && (j==2)
       i=i+1;
       if ((data(i,n)+p)*(data(i+1,n)+p)<=0)
        j=i;
       else
        j=2;
       end
end
x1=data(j,1);
y1=data(j,n);
x2=data(j+1,1);
y2=data(j+1,n);

Length1=x1+((x1-x2)/(y1-y2))*(-p-y1);




k=q;l=2;m=2;

while (k<s) && (m==2)
       k=k+1;
       if ((data(k,n)+p)*(data(k+1,n)+p)<=0)&&(abs(k-j)>3)
        m=k;
       else
        m=2;
       end
end
x3=data(k,1);
y3=data(k,n);
x4=data(k+1,1);
y4=data(k+1,n);
   
Length2=x3+((x3-x4)/(y3-y4))*(-p-y3);
c=n-1
Length=(Length1+Length2)*0.5
Lengthaq(c,1)=Length;

end