原函数=∫(1/√2)/[x^2(1-1/(√2x)^2)^(1/2)dx，1/√2x=cost，x=1/(√2cost)，dx=(1/√2)sint/(cost)^2dt原函数=∫((cost)^2/sint)(sint/(cost)^2)dt=t+C，t=arccos(1/√2x)原函数=arccos(1/√2x)+C
log(((2*x^2 - 1)^(1/2) + i)/x)*i
