estimate the parameters of an equation

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Nikolas Spiliopoulos
回答： Steven Lord 2017-3-20
Hi there,
I have a question:
I have an equation like this: 45=a*5^b;
is there any way to estimate a and b only from this equation?
thanks
  1 个评论
Adam
Adam 2017-3-20
At a glance, without putting much thought into it I'd imagine there are an infinite number of solutions unless you are restricting yourself to integers only.

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Star Strider
Star Strider 2017-3-20
No.
You are estimating 2 parameters with 1 (x,y) data pair. There is no unique solution.

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Steven Lord
Steven Lord 2017-3-20
Borrowing a problem from Cleve: "I'm thinking of two numbers. Their average is 3. What are the numbers?" I just wrote down my answer; I would be very surprised if you gave the same answer I wrote down.
Like Cleve's question, your question has infinitely many solutions. But if you want the solution for a in terms of b:
syms a b
f = 45 == a*5^b;
asol = solve(f, a)
check = isAlways(subs(f, a, asol))

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