//chapter7
printf("\n");
fcr1=4.5*10^6;
fcr2=1.5*10^6;
Nmax1=(fcr1/9)^2';
Nmax2=(fcr2/9)^2;
printf("the Nmax values are");
printf("\n %gm^3 %gm^3",Nmax1,Nmax2);
Nmax=Nmax1-Nmax2;
printf("\n the change in electron density is %gm^3",Nmax);