get sympy result as trig function rather than complex log
up vote
1
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I'm doing some manipulation of trig equations and would like the results back in trig form.
What I'm doing is this:
from sympy import *
B,D,a=symbols(r'B,D,alpha',real=True,positive=True)
eq1=Eq(D,B*((sin(a)*sin(a))/(sin(a+a))))
solve(eq1,a)
I expect the result to be atan(2*D/B) but I'm getting:
[-I*log(-sqrt((B + 2*I*D)/(B - 2*I*D))), -I*log((B + 2*I*D)/(B - 2*I*D))/2]
I know sympy is expanding the trig functions into exponential form, but I can't seem to convince it to convert the results back.
I've tried:
[n.rewrite(atan) for n in solve(eq1,a)]
but I get the same result back...
python sympy trigonometry
asked Nov 10 at 1:27
Omegaman
784618
add a comment |
up vote
1
down vote
favorite
I'm doing some manipulation of trig equations and would like the results back in trig form.
What I'm doing is this:
from sympy import *
B,D,a=symbols(r'B,D,alpha',real=True,positive=True)
eq1=Eq(D,B*((sin(a)*sin(a))/(sin(a+a))))
solve(eq1,a)
I expect the result to be atan(2*D/B) but I'm getting:
[-I*log(-sqrt((B + 2*I*D)/(B - 2*I*D))), -I*log((B + 2*I*D)/(B - 2*I*D))/2]
I know sympy is expanding the trig functions into exponential form, but I can't seem to convince it to convert the results back.
I've tried:
[n.rewrite(atan) for n in solve(eq1,a)]
but I get the same result back...
python sympy trigonometry
asked Nov 10 at 1:27
Omegaman
784618
have you tried using simplify() or trigsimp() docs.sympy.org/0.7.0/modules/simplify.html#trigsimp
– user1269942
Nov 10 at 1:44
I did try those on the result, without luck. Of course I didn't try them /before/ the solve, which does resove the issue.
– Omegaman
Nov 10 at 2:50
add a comment |
up vote
1
down vote
favorite
up vote
1
down vote
favorite
I'm doing some manipulation of trig equations and would like the results back in trig form.
What I'm doing is this:
from sympy import *
B,D,a=symbols(r'B,D,alpha',real=True,positive=True)
eq1=Eq(D,B*((sin(a)*sin(a))/(sin(a+a))))
solve(eq1,a)
I expect the result to be atan(2*D/B) but I'm getting:
[-I*log(-sqrt((B + 2*I*D)/(B - 2*I*D))), -I*log((B + 2*I*D)/(B - 2*I*D))/2]
I know sympy is expanding the trig functions into exponential form, but I can't seem to convince it to convert the results back.
I've tried:
[n.rewrite(atan) for n in solve(eq1,a)]
but I get the same result back...
python sympy trigonometry
asked Nov 10 at 1:27
Omegaman
784618
I'm doing some manipulation of trig equations and would like the results back in trig form.
What I'm doing is this:
from sympy import *
B,D,a=symbols(r'B,D,alpha',real=True,positive=True)
eq1=Eq(D,B*((sin(a)*sin(a))/(sin(a+a))))
solve(eq1,a)
I expect the result to be atan(2*D/B) but I'm getting:
[-I*log(-sqrt((B + 2*I*D)/(B - 2*I*D))), -I*log((B + 2*I*D)/(B - 2*I*D))/2]
I know sympy is expanding the trig functions into exponential form, but I can't seem to convince it to convert the results back.
I've tried:
[n.rewrite(atan) for n in solve(eq1,a)]
but I get the same result back...
python sympy trigonometry
python sympy trigonometry
asked Nov 10 at 1:27
Omegaman
784618
asked Nov 10 at 1:27
Omegaman
784618
asked Nov 10 at 1:27
Omegaman
784618
asked Nov 10 at 1:27
Omegaman
784618
asked Nov 10 at 1:27
Omegaman
784618
784618
have you tried using simplify() or trigsimp() docs.sympy.org/0.7.0/modules/simplify.html#trigsimp
– user1269942
Nov 10 at 1:44
I did try those on the result, without luck. Of course I didn't try them /before/ the solve, which does resove the issue.
– Omegaman
Nov 10 at 2:50
add a comment |
have you tried using simplify() or trigsimp() docs.sympy.org/0.7.0/modules/simplify.html#trigsimp
– user1269942
Nov 10 at 1:44
I did try those on the result, without luck. Of course I didn't try them /before/ the solve, which does resove the issue.
– Omegaman
Nov 10 at 2:50
have you tried using simplify() or trigsimp() docs.sympy.org/0.7.0/modules/simplify.html#trigsimp
– user1269942
Nov 10 at 1:44
have you tried using simplify() or trigsimp() docs.sympy.org/0.7.0/modules/simplify.html#trigsimp
– user1269942
Nov 10 at 1:44
I did try those on the result, without luck. Of course I didn't try them /before/ the solve, which does resove the issue.
– Omegaman
Nov 10 at 2:50
I did try those on the result, without luck. Of course I didn't try them /before/ the solve, which does resove the issue.
– Omegaman
Nov 10 at 2:50
add a comment |
1 Answer
1
active
oldest
votes
up vote
1
down vote
accepted
If you simplify before solving, the result looks better.
>>> solve(eq1.simplify(), a)
[atan(2*D/B)]
Also, the more mathematically rigorous solveset (a modern alternative to solve) returns a more mathematically correct answer without the need for simplification:
>>> solveset(eq1, a)
ConditionSet(alpha, Eq(tan(alpha)/2 - D/B, 0), Reals)
The point being that there are infinitely many solutions, so they cannot be given as a list: so, solveset presents them as the set of all alpha such that tan(alpha) is 2*D/B.
In this case, I'm using it for engineering purposes so the one solution is enough... ;-) Thanks. Tried every way I could think of to fix the output, didn't think to tweak the input.
– Omegaman
Nov 10 at 2:49
add a comment |
1 Answer
1
active
oldest
votes
1 Answer
1
active
oldest
votes
active
oldest
votes
active
oldest
votes
up vote
1
down vote
accepted
If you simplify before solving, the result looks better.
>>> solve(eq1.simplify(), a)
[atan(2*D/B)]
Also, the more mathematically rigorous solveset (a modern alternative to solve) returns a more mathematically correct answer without the need for simplification:
>>> solveset(eq1, a)
ConditionSet(alpha, Eq(tan(alpha)/2 - D/B, 0), Reals)
The point being that there are infinitely many solutions, so they cannot be given as a list: so, solveset presents them as the set of all alpha such that tan(alpha) is 2*D/B.
In this case, I'm using it for engineering purposes so the one solution is enough... ;-) Thanks. Tried every way I could think of to fix the output, didn't think to tweak the input.
– Omegaman
Nov 10 at 2:49
add a comment |
up vote
1
down vote
accepted
If you simplify before solving, the result looks better.
>>> solve(eq1.simplify(), a)
[atan(2*D/B)]
Also, the more mathematically rigorous solveset (a modern alternative to solve) returns a more mathematically correct answer without the need for simplification:
>>> solveset(eq1, a)
ConditionSet(alpha, Eq(tan(alpha)/2 - D/B, 0), Reals)
The point being that there are infinitely many solutions, so they cannot be given as a list: so, solveset presents them as the set of all alpha such that tan(alpha) is 2*D/B.
In this case, I'm using it for engineering purposes so the one solution is enough... ;-) Thanks. Tried every way I could think of to fix the output, didn't think to tweak the input.
– Omegaman
Nov 10 at 2:49
add a comment |
up vote
1
down vote
accepted
up vote
1
down vote
accepted
If you simplify before solving, the result looks better.
>>> solve(eq1.simplify(), a)
[atan(2*D/B)]
Also, the more mathematically rigorous solveset (a modern alternative to solve) returns a more mathematically correct answer without the need for simplification:
>>> solveset(eq1, a)
ConditionSet(alpha, Eq(tan(alpha)/2 - D/B, 0), Reals)
The point being that there are infinitely many solutions, so they cannot be given as a list: so, solveset presents them as the set of all alpha such that tan(alpha) is 2*D/B.
If you simplify before solving, the result looks better.
>>> solve(eq1.simplify(), a)
[atan(2*D/B)]
Also, the more mathematically rigorous solveset (a modern alternative to solve) returns a more mathematically correct answer without the need for simplification:
>>> solveset(eq1, a)
ConditionSet(alpha, Eq(tan(alpha)/2 - D/B, 0), Reals)
The point being that there are infinitely many solutions, so they cannot be given as a list: so, solveset presents them as the set of all alpha such that tan(alpha) is 2*D/B.
answered Nov 10 at 2:25
user6655984
In this case, I'm using it for engineering purposes so the one solution is enough... ;-) Thanks. Tried every way I could think of to fix the output, didn't think to tweak the input.
– Omegaman
Nov 10 at 2:49
add a comment |
In this case, I'm using it for engineering purposes so the one solution is enough... ;-) Thanks. Tried every way I could think of to fix the output, didn't think to tweak the input.
– Omegaman
Nov 10 at 2:49
In this case, I'm using it for engineering purposes so the one solution is enough... ;-) Thanks. Tried every way I could think of to fix the output, didn't think to tweak the input.
– Omegaman
Nov 10 at 2:49
In this case, I'm using it for engineering purposes so the one solution is enough... ;-) Thanks. Tried every way I could think of to fix the output, didn't think to tweak the input.
– Omegaman
Nov 10 at 2:49
add a comment |
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have you tried using simplify() or trigsimp() docs.sympy.org/0.7.0/modules/simplify.html#trigsimp
– user1269942
Nov 10 at 1:44
I did try those on the result, without luck. Of course I didn't try them /before/ the solve, which does resove the issue.
– Omegaman
Nov 10 at 2:50