11-09-2014, 02:29 PM
A diff() problem:
Example: f(x,y):+x²-2*x*y+3*y²+2*x-2*y
1.) diff(f(x,y),x) ---> 2.*x-2.*y+2.
2.) diff(f(x,y),y) ---> -2*x+6*y-2
x - direction:
3.) diff(diff(f(x,y),x)) ---> 2
4.) diff( 2.*x-2.*y+2,x) ---> 2
5.) diff(f(x,y),x$2) ---> 2
y - direction:
6.) diff(diff(f(x,y),y)) ---> -2
7.) diff(-2*x+6*y-2,y) ---> 6
8.) diff(f(x,y),y$2) ---> 6
The second derivative in the x-direction worked properly.
The second derivative in the y-direction worked improperly in the red highlighted case(??)
(The template key entry method worked properly for these examples.)
Example: f(x,y):+x²-2*x*y+3*y²+2*x-2*y
1.) diff(f(x,y),x) ---> 2.*x-2.*y+2.
2.) diff(f(x,y),y) ---> -2*x+6*y-2
x - direction:
3.) diff(diff(f(x,y),x)) ---> 2
4.) diff( 2.*x-2.*y+2,x) ---> 2
5.) diff(f(x,y),x$2) ---> 2
y - direction:
6.) diff(diff(f(x,y),y)) ---> -2
7.) diff(-2*x+6*y-2,y) ---> 6
8.) diff(f(x,y),y$2) ---> 6
The second derivative in the x-direction worked properly.
The second derivative in the y-direction worked improperly in the red highlighted case(??)
(The template key entry method worked properly for these examples.)