How to extract the argument from an in-built function
I would like to extract the argument from :
DiracDelta[-10 + x + ξ]
extract
asked Dec 13 '18 at 14:55
Riccardo
285
add a comment |
I would like to extract the argument from :
DiracDelta[-10 + x + ξ]
extract
asked Dec 13 '18 at 14:55
Riccardo
285
add a comment |
I would like to extract the argument from :
DiracDelta[-10 + x + ξ]
extract
asked Dec 13 '18 at 14:55
Riccardo
285
I would like to extract the argument from :
DiracDelta[-10 + x + ξ]
extract
extract
asked Dec 13 '18 at 14:55
Riccardo
285
asked Dec 13 '18 at 14:55
Riccardo
285
edited Dec 13 '18 at 16:02
asked Dec 13 '18 at 14:55
Riccardo
285
asked Dec 13 '18 at 14:55
Riccardo
285
asked Dec 13 '18 at 14:55
Riccardo
285
285
add a comment |
add a comment |
3 Answers
3
active
oldest
votes
You can use Part to access the parts of any normal expression.
DiracDelta[-10 + x + ξ][[1]]
(* -10 + x + ξ *)
In this case you can also use First since you want the first part.
Another common need is to pull out the arguments of a function when that function is buried in a larger expression. For this you can use Cases
Cases[
{w''[z] + k^2 w[z] == DiracDelta[z], w[0] == 0, w'[0] == 1},
DiracDelta[arg_] :> arg, Infinity]
(* {z} *)
answered Dec 13 '18 at 15:04
Jason B.
47.7k387186
add a comment |
What about
DiracDelta[-10 + x + [Xi]] /. DiracDelta -> Identity
(**)
More generally(also works for several arguments)
Apply[List ,DiracDelta[-10 + x + [Xi]] ]
answered Dec 13 '18 at 17:12
Ulrich Neumann
7,320515
add a comment |
DiracDelta[-10 + x + [Xi]] /. DiracDelta -> " "
or (as @JasonB wrote):
First@DiracDelta[-10 + x + [Xi]]
answered Dec 13 '18 at 15:21
David G. Stork
23.3k22051
add a comment |
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3 Answers
3
active
oldest
votes
3 Answers
3
active
oldest
votes
active
oldest
votes
active
oldest
votes
You can use Part to access the parts of any normal expression.
DiracDelta[-10 + x + ξ][[1]]
(* -10 + x + ξ *)
In this case you can also use First since you want the first part.
Another common need is to pull out the arguments of a function when that function is buried in a larger expression. For this you can use Cases
Cases[
{w''[z] + k^2 w[z] == DiracDelta[z], w[0] == 0, w'[0] == 1},
DiracDelta[arg_] :> arg, Infinity]
(* {z} *)
answered Dec 13 '18 at 15:04
Jason B.
47.7k387186
add a comment |
You can use Part to access the parts of any normal expression.
DiracDelta[-10 + x + ξ][[1]]
(* -10 + x + ξ *)
In this case you can also use First since you want the first part.
Another common need is to pull out the arguments of a function when that function is buried in a larger expression. For this you can use Cases
Cases[
{w''[z] + k^2 w[z] == DiracDelta[z], w[0] == 0, w'[0] == 1},
DiracDelta[arg_] :> arg, Infinity]
(* {z} *)
answered Dec 13 '18 at 15:04
Jason B.
47.7k387186
add a comment |
You can use Part to access the parts of any normal expression.
DiracDelta[-10 + x + ξ][[1]]
(* -10 + x + ξ *)
In this case you can also use First since you want the first part.
Another common need is to pull out the arguments of a function when that function is buried in a larger expression. For this you can use Cases
Cases[
{w''[z] + k^2 w[z] == DiracDelta[z], w[0] == 0, w'[0] == 1},
DiracDelta[arg_] :> arg, Infinity]
(* {z} *)
answered Dec 13 '18 at 15:04
Jason B.
47.7k387186
You can use Part to access the parts of any normal expression.
DiracDelta[-10 + x + ξ][[1]]
(* -10 + x + ξ *)
In this case you can also use First since you want the first part.
Another common need is to pull out the arguments of a function when that function is buried in a larger expression. For this you can use Cases
Cases[
{w''[z] + k^2 w[z] == DiracDelta[z], w[0] == 0, w'[0] == 1},
DiracDelta[arg_] :> arg, Infinity]
(* {z} *)
answered Dec 13 '18 at 15:04
Jason B.
47.7k387186
edited Dec 13 '18 at 15:55
answered Dec 13 '18 at 15:04
Jason B.
47.7k387186
answered Dec 13 '18 at 15:04
Jason B.
47.7k387186
answered Dec 13 '18 at 15:04
Jason B.
47.7k387186
47.7k387186
add a comment |
add a comment |
What about
DiracDelta[-10 + x + [Xi]] /. DiracDelta -> Identity
(**)
More generally(also works for several arguments)
Apply[List ,DiracDelta[-10 + x + [Xi]] ]
answered Dec 13 '18 at 17:12
Ulrich Neumann
7,320515
add a comment |
What about
DiracDelta[-10 + x + [Xi]] /. DiracDelta -> Identity
(**)
More generally(also works for several arguments)
Apply[List ,DiracDelta[-10 + x + [Xi]] ]
answered Dec 13 '18 at 17:12
Ulrich Neumann
7,320515
add a comment |
What about
DiracDelta[-10 + x + [Xi]] /. DiracDelta -> Identity
(**)
More generally(also works for several arguments)
Apply[List ,DiracDelta[-10 + x + [Xi]] ]
answered Dec 13 '18 at 17:12
Ulrich Neumann
7,320515
What about
DiracDelta[-10 + x + [Xi]] /. DiracDelta -> Identity
(**)
More generally(also works for several arguments)
Apply[List ,DiracDelta[-10 + x + [Xi]] ]
answered Dec 13 '18 at 17:12
Ulrich Neumann
7,320515
answered Dec 13 '18 at 17:12
Ulrich Neumann
7,320515
answered Dec 13 '18 at 17:12
Ulrich Neumann
7,320515
answered Dec 13 '18 at 17:12
Ulrich Neumann
7,320515
7,320515
add a comment |
add a comment |
DiracDelta[-10 + x + [Xi]] /. DiracDelta -> " "
or (as @JasonB wrote):
First@DiracDelta[-10 + x + [Xi]]
answered Dec 13 '18 at 15:21
David G. Stork
23.3k22051
add a comment |
DiracDelta[-10 + x + [Xi]] /. DiracDelta -> " "
or (as @JasonB wrote):
First@DiracDelta[-10 + x + [Xi]]
answered Dec 13 '18 at 15:21
David G. Stork
23.3k22051
add a comment |
DiracDelta[-10 + x + [Xi]] /. DiracDelta -> " "
or (as @JasonB wrote):
First@DiracDelta[-10 + x + [Xi]]
answered Dec 13 '18 at 15:21
David G. Stork
23.3k22051
DiracDelta[-10 + x + [Xi]] /. DiracDelta -> " "
or (as @JasonB wrote):
First@DiracDelta[-10 + x + [Xi]]
answered Dec 13 '18 at 15:21
David G. Stork
23.3k22051
answered Dec 13 '18 at 15:21
David G. Stork
23.3k22051
answered Dec 13 '18 at 15:21
David G. Stork
23.3k22051
answered Dec 13 '18 at 15:21
David G. Stork
23.3k22051
23.3k22051
add a comment |
add a comment |
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