m2=3*e*e*m0/2;
m4=5*e*e*m2/4; m6=7*e*e*m4/6; m8=9*e*e*m6/8;
a0=m0+m2/2+3*m4/8+5*m6/16+35*m8/128; a2=m2/2+m4/2+15*m6/32+7*m8/16; a4=m4/8+3*m6/16+7*m8/32; a6=m6/32+m8/16; a8=m8/128;
B1=g[i].x/a0; do {
F=-a2*sin(2*B1)/2+a4*sin(4*B1)/4-a6*sin(6*B1)/6+a8*sin(8*B
1)/8;
} while(fabs(B3-B2)>10e-10);//利用迭代算法求解底点纬度// return B2;
B2=(g[i].x-F)/a0; B3=B1; B1=B2;
}