Question about Draft calculation

I calculate stablility by software "COMPASS"(CHINA CLASSIFFICATION SOCIETY's) usually.
I want to make a software by java which can create a excelfile contain all calculation's results(likes summary table).
Now,i have a program, the draft i cal is not the same as software .
I dont konw which formula is wrong.
Any one can help me ,thanks in advance!
following is partical code:

/*(double dis,double L,double draftAv,double Xg,double Xb,double Mtc,double Xf
* ,double zg,double zb,double bM,double wi) those are konwn
*/
public IntactStability(double dis,double L,double draftAv,double Xg,double Xb,double Mtc,double Xf
,double zg,double zb,double bM,double wi){

this.dis=dis;
this.L=L;
this.draftAv=draftAv;
this.Xg=Xg;
this.Xb=Xb;
this.trimArm=Xg-Xb;
this.trimMoment=dis*trimArm;
this.Mtc=Mtc;
this.trim=trimMoment/100/Mtc;
this.Xf=Xf;

// from
this.dfChange=(L/2-Xf)*trim/L;
this.daChange=-(L/2+Xf)*trim/L;
this.df=draftAv+dfChange;
this.da=draftAv+daChange;
this.dav=(df+da)/2;

//end
this.zg=zg;
this.zb=zb;
this.bM=bM;
this.zM=zb+bM;
this.GM0=zM-zg;
this.wi=wi;
this.GM1=wi/dis;
this.GM1=GM0-GM1;


}

 

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