I'm trying to solve equation which simplifies to this form:
a^x = b
eg.
solve([(123)^y==(234234)],y)
which returns [y == log(234234)/log(123)]
but solve([(123.123)^y==(234234.123)],y) (having floating point constants)
returns
[123123^y == 234234123*1000^(y - 1)]
How do I get it to return the answer in terms of log.
You can convert the floating point constants to rationals and use Sympy:
sage: y = var("y")
sage: a = 123.123
sage: b = 234234.123
sage: solve(QQ(a)^y==QQ(b), y, algorithm="sympy")
[y == (log(234234123) - 3*log(10))/(log(123123) - 3*log(10))]
It seems that Sympy can also provide a numerical solution if its domain is restricted:
sage: solve(a^y==b, y, algorithm="sympy", domain="real")
[y == 2.56879371128374]
Asked: 2020-06-22 04:02:26 +0100
Seen: 309 times
Last updated: Jun 23 '20
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