How to extract the argument from an in-built function
up vote
3
down vote
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I would like to extract the argument from :
DiracDelta[-10 + x + ξ]
extract
asked 14 hours ago
Riccardo
285
add a comment |
up vote
3
down vote
favorite
I would like to extract the argument from :
DiracDelta[-10 + x + ξ]
extract
asked 14 hours ago
Riccardo
285
add a comment |
up vote
3
down vote
favorite
up vote
3
down vote
favorite
I would like to extract the argument from :
DiracDelta[-10 + x + ξ]
extract
asked 14 hours ago
Riccardo
285
I would like to extract the argument from :
DiracDelta[-10 + x + ξ]
extract
extract
asked 14 hours ago
Riccardo
285
asked 14 hours ago
Riccardo
285
edited 13 hours ago
asked 14 hours ago
Riccardo
285
asked 14 hours ago
Riccardo
285
asked 14 hours ago
Riccardo
285
285
add a comment |
add a comment |
3 Answers
3
active
oldest
votes
up vote
6
down vote
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 14 hours ago
Jason B.
47.6k387185
add a comment |
up vote
2
down vote
DiracDelta[-10 + x + [Xi]] /. DiracDelta -> " "
or (as @JasonB wrote):
First@DiracDelta[-10 + x + [Xi]]
answered 13 hours ago
David G. Stork
22.9k22051
add a comment |
up vote
2
down vote
What about
DiracDelta[-10 + x + [Xi]] /. DiracDelta -> Identity
(**)
More generally(also works for several arguments)
Apply[List ,DiracDelta[-10 + x + [Xi]] ]
answered 12 hours ago
Ulrich Neumann
6,530515
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
up vote
6
down vote
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 14 hours ago
Jason B.
47.6k387185
add a comment |
up vote
6
down vote
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 14 hours ago
Jason B.
47.6k387185
add a comment |
up vote
6
down vote
up vote
6
down vote
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 14 hours ago
Jason B.
47.6k387185
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 14 hours ago
Jason B.
47.6k387185
edited 13 hours ago
answered 14 hours ago
Jason B.
47.6k387185
answered 14 hours ago
Jason B.
47.6k387185
answered 14 hours ago
Jason B.
47.6k387185
47.6k387185
add a comment |
add a comment |
up vote
2
down vote
DiracDelta[-10 + x + [Xi]] /. DiracDelta -> " "
or (as @JasonB wrote):
First@DiracDelta[-10 + x + [Xi]]
answered 13 hours ago
David G. Stork
22.9k22051
add a comment |
up vote
2
down vote
DiracDelta[-10 + x + [Xi]] /. DiracDelta -> " "
or (as @JasonB wrote):
First@DiracDelta[-10 + x + [Xi]]
answered 13 hours ago
David G. Stork
22.9k22051
add a comment |
up vote
2
down vote
up vote
2
down vote
DiracDelta[-10 + x + [Xi]] /. DiracDelta -> " "
or (as @JasonB wrote):
First@DiracDelta[-10 + x + [Xi]]
answered 13 hours ago
David G. Stork
22.9k22051
DiracDelta[-10 + x + [Xi]] /. DiracDelta -> " "
or (as @JasonB wrote):
First@DiracDelta[-10 + x + [Xi]]
answered 13 hours ago
David G. Stork
22.9k22051
answered 13 hours ago
David G. Stork
22.9k22051
answered 13 hours ago
David G. Stork
22.9k22051
answered 13 hours ago
David G. Stork
22.9k22051
22.9k22051
add a comment |
add a comment |
up vote
2
down vote
What about
DiracDelta[-10 + x + [Xi]] /. DiracDelta -> Identity
(**)
More generally(also works for several arguments)
Apply[List ,DiracDelta[-10 + x + [Xi]] ]
answered 12 hours ago
Ulrich Neumann
6,530515
add a comment |
up vote
2
down vote
What about
DiracDelta[-10 + x + [Xi]] /. DiracDelta -> Identity
(**)
More generally(also works for several arguments)
Apply[List ,DiracDelta[-10 + x + [Xi]] ]
answered 12 hours ago
Ulrich Neumann
6,530515
add a comment |
up vote
2
down vote
up vote
2
down vote
What about
DiracDelta[-10 + x + [Xi]] /. DiracDelta -> Identity
(**)
More generally(also works for several arguments)
Apply[List ,DiracDelta[-10 + x + [Xi]] ]
answered 12 hours ago
Ulrich Neumann
6,530515
What about
DiracDelta[-10 + x + [Xi]] /. DiracDelta -> Identity
(**)
More generally(also works for several arguments)
Apply[List ,DiracDelta[-10 + x + [Xi]] ]
answered 12 hours ago
Ulrich Neumann
6,530515
answered 12 hours ago
Ulrich Neumann
6,530515
answered 12 hours ago
Ulrich Neumann
6,530515
answered 12 hours ago
Ulrich Neumann
6,530515
6,530515
add a comment |
add a comment |
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