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Are these expressions not equal? Mathematica output is ambiguous
Checking if two trigonometric expressions are equalHow to group the powers of one variable?How do I simplify an embedded sub-expression without affecting other sub-expressions?Why are some equal expressions more equal than others?How can I get Mathematica to simplify my expression?Equality of Reciprocal with Negative ExponentMake Mathematica not simplify an expressionWSTP simplifying expression from CHow do I handle complicated algebraic manipulations?Smart way of simplifying an expression with square roots?
$begingroup$
The following plot indicates that the first expression equals the second. But how can I use Mathematica to show that is true:
Plot[(-(Log[(1 - P)/P]/Log[10])) - (Log[-(P/(-1 + P))]/Log[10]), P, 0, 1]
An attempt to simplify indicates the expressions are not equal:
FullSimplify[(-(Log[(1 - P)/P]/Log[10])) - (Log[-(P/(-1 + P))]/Log[10])]
That gives the following answer:
(Log[-1 + 1/P] + Log[-(P/(-1 + P))])/Log[10]
plotting simplifying-expressions
$endgroup$
add a comment |
$begingroup$
The following plot indicates that the first expression equals the second. But how can I use Mathematica to show that is true:
Plot[(-(Log[(1 - P)/P]/Log[10])) - (Log[-(P/(-1 + P))]/Log[10]), P, 0, 1]
An attempt to simplify indicates the expressions are not equal:
FullSimplify[(-(Log[(1 - P)/P]/Log[10])) - (Log[-(P/(-1 + P))]/Log[10])]
That gives the following answer:
(Log[-1 + 1/P] + Log[-(P/(-1 + P))])/Log[10]
plotting simplifying-expressions
$endgroup$
3
$begingroup$
Add the optionAssumptions -> 0 < P < 1
toFullSimplify
and it will tell you they are the same on that domain. Without assumptions, Mathematica will try to solve the equation for every possible complex value ofP
and the two equations are not generally equal due to branch cuts.
$endgroup$
– Sjoerd Smit
yesterday
1
$begingroup$
In addition to what Sjoerd said: EvaluatingFullSimplify[(-(Log[(1 - P)/P]/Log[10])) - (Log[-(P/(-1 + P))]/ Log[10]), P > 1]
reveals that the expressions are not equal for arbitrary realP
. So Mathematica would have lied if she had simplifiedFullSimplify[(-(Log[(1 - P)/P]/Log[10])) - (Log[-(P/(-1 + P))]/Log[10])]
to0
.
$endgroup$
– Henrik Schumacher
yesterday
1
$begingroup$
Always remember: Mathematica always assumes variables are complex-valued unless told otherwise. You did not tellFullSimplify[]
what you know aboutP
, so of course you get a general result.
$endgroup$
– J. M. is slightly pensive♦
yesterday
add a comment |
$begingroup$
The following plot indicates that the first expression equals the second. But how can I use Mathematica to show that is true:
Plot[(-(Log[(1 - P)/P]/Log[10])) - (Log[-(P/(-1 + P))]/Log[10]), P, 0, 1]
An attempt to simplify indicates the expressions are not equal:
FullSimplify[(-(Log[(1 - P)/P]/Log[10])) - (Log[-(P/(-1 + P))]/Log[10])]
That gives the following answer:
(Log[-1 + 1/P] + Log[-(P/(-1 + P))])/Log[10]
plotting simplifying-expressions
$endgroup$
The following plot indicates that the first expression equals the second. But how can I use Mathematica to show that is true:
Plot[(-(Log[(1 - P)/P]/Log[10])) - (Log[-(P/(-1 + P))]/Log[10]), P, 0, 1]
An attempt to simplify indicates the expressions are not equal:
FullSimplify[(-(Log[(1 - P)/P]/Log[10])) - (Log[-(P/(-1 + P))]/Log[10])]
That gives the following answer:
(Log[-1 + 1/P] + Log[-(P/(-1 + P))])/Log[10]
plotting simplifying-expressions
plotting simplifying-expressions
asked yesterday
user120911user120911
73628
73628
3
$begingroup$
Add the optionAssumptions -> 0 < P < 1
toFullSimplify
and it will tell you they are the same on that domain. Without assumptions, Mathematica will try to solve the equation for every possible complex value ofP
and the two equations are not generally equal due to branch cuts.
$endgroup$
– Sjoerd Smit
yesterday
1
$begingroup$
In addition to what Sjoerd said: EvaluatingFullSimplify[(-(Log[(1 - P)/P]/Log[10])) - (Log[-(P/(-1 + P))]/ Log[10]), P > 1]
reveals that the expressions are not equal for arbitrary realP
. So Mathematica would have lied if she had simplifiedFullSimplify[(-(Log[(1 - P)/P]/Log[10])) - (Log[-(P/(-1 + P))]/Log[10])]
to0
.
$endgroup$
– Henrik Schumacher
yesterday
1
$begingroup$
Always remember: Mathematica always assumes variables are complex-valued unless told otherwise. You did not tellFullSimplify[]
what you know aboutP
, so of course you get a general result.
$endgroup$
– J. M. is slightly pensive♦
yesterday
add a comment |
3
$begingroup$
Add the optionAssumptions -> 0 < P < 1
toFullSimplify
and it will tell you they are the same on that domain. Without assumptions, Mathematica will try to solve the equation for every possible complex value ofP
and the two equations are not generally equal due to branch cuts.
$endgroup$
– Sjoerd Smit
yesterday
1
$begingroup$
In addition to what Sjoerd said: EvaluatingFullSimplify[(-(Log[(1 - P)/P]/Log[10])) - (Log[-(P/(-1 + P))]/ Log[10]), P > 1]
reveals that the expressions are not equal for arbitrary realP
. So Mathematica would have lied if she had simplifiedFullSimplify[(-(Log[(1 - P)/P]/Log[10])) - (Log[-(P/(-1 + P))]/Log[10])]
to0
.
$endgroup$
– Henrik Schumacher
yesterday
1
$begingroup$
Always remember: Mathematica always assumes variables are complex-valued unless told otherwise. You did not tellFullSimplify[]
what you know aboutP
, so of course you get a general result.
$endgroup$
– J. M. is slightly pensive♦
yesterday
3
3
$begingroup$
Add the option
Assumptions -> 0 < P < 1
to FullSimplify
and it will tell you they are the same on that domain. Without assumptions, Mathematica will try to solve the equation for every possible complex value of P
and the two equations are not generally equal due to branch cuts.$endgroup$
– Sjoerd Smit
yesterday
$begingroup$
Add the option
Assumptions -> 0 < P < 1
to FullSimplify
and it will tell you they are the same on that domain. Without assumptions, Mathematica will try to solve the equation for every possible complex value of P
and the two equations are not generally equal due to branch cuts.$endgroup$
– Sjoerd Smit
yesterday
1
1
$begingroup$
In addition to what Sjoerd said: Evaluating
FullSimplify[(-(Log[(1 - P)/P]/Log[10])) - (Log[-(P/(-1 + P))]/ Log[10]), P > 1]
reveals that the expressions are not equal for arbitrary real P
. So Mathematica would have lied if she had simplified FullSimplify[(-(Log[(1 - P)/P]/Log[10])) - (Log[-(P/(-1 + P))]/Log[10])]
to 0
.$endgroup$
– Henrik Schumacher
yesterday
$begingroup$
In addition to what Sjoerd said: Evaluating
FullSimplify[(-(Log[(1 - P)/P]/Log[10])) - (Log[-(P/(-1 + P))]/ Log[10]), P > 1]
reveals that the expressions are not equal for arbitrary real P
. So Mathematica would have lied if she had simplified FullSimplify[(-(Log[(1 - P)/P]/Log[10])) - (Log[-(P/(-1 + P))]/Log[10])]
to 0
.$endgroup$
– Henrik Schumacher
yesterday
1
1
$begingroup$
Always remember: Mathematica always assumes variables are complex-valued unless told otherwise. You did not tell
FullSimplify[]
what you know about P
, so of course you get a general result.$endgroup$
– J. M. is slightly pensive♦
yesterday
$begingroup$
Always remember: Mathematica always assumes variables are complex-valued unless told otherwise. You did not tell
FullSimplify[]
what you know about P
, so of course you get a general result.$endgroup$
– J. M. is slightly pensive♦
yesterday
add a comment |
1 Answer
1
active
oldest
votes
$begingroup$
You can ask Mathematica when this expression is zero, assuming we work on the reals:
Reduce[(-(Log[(1 - P)/P]/Log[10])) - (Log[-(P/(-1 + P))]/Log[10]) == 0, P, Reals]
(* 0 < P < 1 *)
FullSimplify
will confirm that result.
FullSimplify[(-(Log[(1 - P)/P]/Log[10])) - (Log[-(P/(-1 + P))]/Log[10]), 0 < P < 1]
(* 0 *)
$endgroup$
add a comment |
Your Answer
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1 Answer
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active
oldest
votes
1 Answer
1
active
oldest
votes
active
oldest
votes
active
oldest
votes
$begingroup$
You can ask Mathematica when this expression is zero, assuming we work on the reals:
Reduce[(-(Log[(1 - P)/P]/Log[10])) - (Log[-(P/(-1 + P))]/Log[10]) == 0, P, Reals]
(* 0 < P < 1 *)
FullSimplify
will confirm that result.
FullSimplify[(-(Log[(1 - P)/P]/Log[10])) - (Log[-(P/(-1 + P))]/Log[10]), 0 < P < 1]
(* 0 *)
$endgroup$
add a comment |
$begingroup$
You can ask Mathematica when this expression is zero, assuming we work on the reals:
Reduce[(-(Log[(1 - P)/P]/Log[10])) - (Log[-(P/(-1 + P))]/Log[10]) == 0, P, Reals]
(* 0 < P < 1 *)
FullSimplify
will confirm that result.
FullSimplify[(-(Log[(1 - P)/P]/Log[10])) - (Log[-(P/(-1 + P))]/Log[10]), 0 < P < 1]
(* 0 *)
$endgroup$
add a comment |
$begingroup$
You can ask Mathematica when this expression is zero, assuming we work on the reals:
Reduce[(-(Log[(1 - P)/P]/Log[10])) - (Log[-(P/(-1 + P))]/Log[10]) == 0, P, Reals]
(* 0 < P < 1 *)
FullSimplify
will confirm that result.
FullSimplify[(-(Log[(1 - P)/P]/Log[10])) - (Log[-(P/(-1 + P))]/Log[10]), 0 < P < 1]
(* 0 *)
$endgroup$
You can ask Mathematica when this expression is zero, assuming we work on the reals:
Reduce[(-(Log[(1 - P)/P]/Log[10])) - (Log[-(P/(-1 + P))]/Log[10]) == 0, P, Reals]
(* 0 < P < 1 *)
FullSimplify
will confirm that result.
FullSimplify[(-(Log[(1 - P)/P]/Log[10])) - (Log[-(P/(-1 + P))]/Log[10]), 0 < P < 1]
(* 0 *)
answered yesterday
SzabolcsSzabolcs
162k14444942
162k14444942
add a comment |
add a comment |
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3
$begingroup$
Add the option
Assumptions -> 0 < P < 1
toFullSimplify
and it will tell you they are the same on that domain. Without assumptions, Mathematica will try to solve the equation for every possible complex value ofP
and the two equations are not generally equal due to branch cuts.$endgroup$
– Sjoerd Smit
yesterday
1
$begingroup$
In addition to what Sjoerd said: Evaluating
FullSimplify[(-(Log[(1 - P)/P]/Log[10])) - (Log[-(P/(-1 + P))]/ Log[10]), P > 1]
reveals that the expressions are not equal for arbitrary realP
. So Mathematica would have lied if she had simplifiedFullSimplify[(-(Log[(1 - P)/P]/Log[10])) - (Log[-(P/(-1 + P))]/Log[10])]
to0
.$endgroup$
– Henrik Schumacher
yesterday
1
$begingroup$
Always remember: Mathematica always assumes variables are complex-valued unless told otherwise. You did not tell
FullSimplify[]
what you know aboutP
, so of course you get a general result.$endgroup$
– J. M. is slightly pensive♦
yesterday