List of invertible congruence classes
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I am attempting to create a list of the invertible congruence classes $bmod 120$.
The code I have is Table[If[{ModularInverse[i, 120]} = {}, 120, ModularInverse[i, 120]], {i,
0, 119}]
If the modular inverse does not exist, it should return $120$. If it does exist, it should return the integer that corresponds to the inverse congruence class.
The code is not working how I expected it to. If the modular inverse does not exists, it gives me a list with the unevaluated code, for example, ModularInverse[0, 120].
table modular-arithmetic
asked 5 hours ago
pmacpmac
182
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add a comment |
$begingroup$
I am attempting to create a list of the invertible congruence classes $bmod 120$.
The code I have is Table[If[{ModularInverse[i, 120]} = {}, 120, ModularInverse[i, 120]], {i,
0, 119}]
If the modular inverse does not exist, it should return $120$. If it does exist, it should return the integer that corresponds to the inverse congruence class.
The code is not working how I expected it to. If the modular inverse does not exists, it gives me a list with the unevaluated code, for example, ModularInverse[0, 120].
table modular-arithmetic
asked 5 hours ago
pmacpmac
182
$endgroup$
$begingroup$
Not the only problem, but one thing to note: Equality is tested with a double-equals==.
$endgroup$
– Michael E2
4 hours ago
add a comment |
$begingroup$
I am attempting to create a list of the invertible congruence classes $bmod 120$.
The code I have is Table[If[{ModularInverse[i, 120]} = {}, 120, ModularInverse[i, 120]], {i,
0, 119}]
If the modular inverse does not exist, it should return $120$. If it does exist, it should return the integer that corresponds to the inverse congruence class.
The code is not working how I expected it to. If the modular inverse does not exists, it gives me a list with the unevaluated code, for example, ModularInverse[0, 120].
table modular-arithmetic
asked 5 hours ago
pmacpmac
182
$endgroup$
I am attempting to create a list of the invertible congruence classes $bmod 120$.
The code I have is Table[If[{ModularInverse[i, 120]} = {}, 120, ModularInverse[i, 120]], {i,
0, 119}]
If the modular inverse does not exist, it should return $120$. If it does exist, it should return the integer that corresponds to the inverse congruence class.
The code is not working how I expected it to. If the modular inverse does not exists, it gives me a list with the unevaluated code, for example, ModularInverse[0, 120].
table modular-arithmetic
table modular-arithmetic
asked 5 hours ago
pmacpmac
182
asked 5 hours ago
pmacpmac
182
asked 5 hours ago
pmacpmac
182
asked 5 hours ago
pmacpmac
182
asked 5 hours ago
pmacpmac
182
182
$begingroup$
Not the only problem, but one thing to note: Equality is tested with a double-equals==.
$endgroup$
– Michael E2
4 hours ago
add a comment |
$begingroup$
Not the only problem, but one thing to note: Equality is tested with a double-equals==.
$endgroup$
– Michael E2
4 hours ago
$begingroup$
Not the only problem, but one thing to note: Equality is tested with a double-equals
==.$endgroup$
– Michael E2
4 hours ago
$begingroup$
Not the only problem, but one thing to note: Equality is tested with a double-equals
==.$endgroup$
– Michael E2
4 hours ago
add a comment |
1 Answer
1
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$begingroup$
Note what happens when i does not have an inverse:
ModularInverse[2, 120]
ModularInverse::ninv: 2 is not invertible modulo 120.
(* Out= ModularInverse[2, 120] *)
The output is the same as the input (it returns "unevaluated" in Mma jargon).
You can use FreeQ to see if the inverse returned unevaluated:
Table[With[{inv = Quiet@ModularInverse[i, 120]},
If[FreeQ[inv, ModularInverse], inv, 120]], {i, 0, 119}]
answered 4 hours ago
Michael E2Michael E2
148k12198475
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add a comment |
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1 Answer
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1 Answer
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active
oldest
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$begingroup$
Note what happens when i does not have an inverse:
ModularInverse[2, 120]
ModularInverse::ninv: 2 is not invertible modulo 120.
(* Out= ModularInverse[2, 120] *)
The output is the same as the input (it returns "unevaluated" in Mma jargon).
You can use FreeQ to see if the inverse returned unevaluated:
Table[With[{inv = Quiet@ModularInverse[i, 120]},
If[FreeQ[inv, ModularInverse], inv, 120]], {i, 0, 119}]
answered 4 hours ago
Michael E2Michael E2
148k12198475
$endgroup$
add a comment |
$begingroup$
Note what happens when i does not have an inverse:
ModularInverse[2, 120]
ModularInverse::ninv: 2 is not invertible modulo 120.
(* Out= ModularInverse[2, 120] *)
The output is the same as the input (it returns "unevaluated" in Mma jargon).
You can use FreeQ to see if the inverse returned unevaluated:
Table[With[{inv = Quiet@ModularInverse[i, 120]},
If[FreeQ[inv, ModularInverse], inv, 120]], {i, 0, 119}]
answered 4 hours ago
Michael E2Michael E2
148k12198475
$endgroup$
add a comment |
$begingroup$
Note what happens when i does not have an inverse:
ModularInverse[2, 120]
ModularInverse::ninv: 2 is not invertible modulo 120.
(* Out= ModularInverse[2, 120] *)
The output is the same as the input (it returns "unevaluated" in Mma jargon).
You can use FreeQ to see if the inverse returned unevaluated:
Table[With[{inv = Quiet@ModularInverse[i, 120]},
If[FreeQ[inv, ModularInverse], inv, 120]], {i, 0, 119}]
answered 4 hours ago
Michael E2Michael E2
148k12198475
$endgroup$
Note what happens when i does not have an inverse:
ModularInverse[2, 120]
ModularInverse::ninv: 2 is not invertible modulo 120.
(* Out= ModularInverse[2, 120] *)
The output is the same as the input (it returns "unevaluated" in Mma jargon).
You can use FreeQ to see if the inverse returned unevaluated:
Table[With[{inv = Quiet@ModularInverse[i, 120]},
If[FreeQ[inv, ModularInverse], inv, 120]], {i, 0, 119}]
answered 4 hours ago
Michael E2Michael E2
148k12198475
answered 4 hours ago
Michael E2Michael E2
148k12198475
answered 4 hours ago
Michael E2Michael E2
148k12198475
answered 4 hours ago
Michael E2Michael E2
148k12198475
148k12198475
add a comment |
add a comment |
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$begingroup$
Not the only problem, but one thing to note: Equality is tested with a double-equals
==.$endgroup$
– Michael E2
4 hours ago