fortran下龙格-库塔法求解常微分方程(实例)(共3页).docx

1.二阶龙格库塔法实例：，程序代码：DIMENSION x(0:20),y(0:20),z(0:20),p(0:21)DOUBLE PRECISION x,y,z,p,h,x0,y0,z0,p0,n,k1,k2f(x,y)=x-yh=1.0/20n=20x(0)=0.0y(0)=0.0DO i=0,n-1 x(i+1)=x(i)+h k1=f(x(i),y(i) k2=f(x(i+1),y(i)+h*k1) y(i+1)=y(i)+h*(k1+k2)/2ENDDOp(0)=0DO i=0,n z(i)=p(i)+exp(-p(i)-1 p(i+1)=p(i)+hEND DOopen(10,file=1.txt)WRITE(10,10) (x(i),y(i),z(i),i=0,20)WRITE(*,10) (x(i),y(i),z(i),i=0,20)10FORMAT(1x,f10.7,2x,f10.8,2x,f10.8/)END