lawrence 初学者,将二阶降为了一阶 (1+x)y"=sqrt(1+y^2)/5 程序总是有报警 library(deSolve) chase=function(x,y,mu){ list(c( y[2], 1/mu*sqrt(1+y[1]^2)/(1-x))) } yini=c(y1=0,y2=0) de=ode(y=yini,func=chase,times=seq(0,2,0.01),parms=5)