二维变换中连续变量中求jacobi（雅克比）行列式

 

 

>

>  x=expression((u+v)/2) 

x 

expression((u + v)/2)

> D(x,'u') 1/2

> D(x,'v') 1/2

> y=expression((u-v)/2)

 > D(x,'v') -(1/2)

> D(x,'u') 1/2

> j<-matrix(c(1/2,1/2,1/2,-1/2),nrow=2) > j  [,1] [,2]
[1,]  0.5  0.5
[2,]  0.5 -0.5

 > det(j) [1] -0.5