1

Input values I have (4 values) are:

0.00    0.25    0.50    0.75

and for each, respectively, I want this output:

0.50    0.54    0.58    0.62

what's the function for this? I don't know how to pull out the ratio:

a => a * ratio
markzzz
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  • If it a function of the type $f(x)=\text{ratio}\cdot x$ you would have $f(0)=0$ which is clearly not the case here. Try to plot the values and guess the function if you want a better interpolation. – Listing Jan 17 '14 at 10:55

3 Answers3

3

The function is $y=0.50+\frac{x}{0.25}\times 0.04=0.5+0.16x$.

1

You may use Maple to find the function:

[> with(CurveFitting):
[> PolynomialInterpolation([[0., .50], [.25, .54], [.50, .58], [.75, .62]], x);

                                 0.16 x + 0.50
Mikasa
  • 67,374
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    @SamiBenRomdhane: Thanks my brother. BTW, here in my country is the celebration of Muhammad (s)'s birthday. Happy to you and all our nations. – Mikasa Jan 18 '14 at 19:45
0

The linear function $f$ mapping $[a,b]$ onto $[c,d]$ (in that order) is $f(x)=c+(\frac{d-c}{b-a})(x-a)$. This assumes $b\neq a$. This maps the end points correctly, and you can check whether or not the interior points in question are also mapped correctly. If they are, this is your linear function. If they are not, there is no such function.

MPW
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