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What formula to chose a nonlinear formula?
Numerical integration of a dataset with method other than the trapezoidal ruleHow To Create a Non-Linear Output from a Linear Input?What is the simplest formula for activation / smooth step function?Process For Building a Function?“Proportional to” - but nonlinear.Range of nonlinear functionFunctional equation - nonlinearAsymptotic functions with derivatives that are $1/2^x$Validating a function over a domain in a computer program.(nonlinear) Regression, but: What type of function is this?What is the most simple formula to achieve this pattern?
$begingroup$
Suppose I have a formula
$$f(x) = x,$$
where $0 leq x leq 255$
Now I want to have a formula
$$f(x) = y,$$
where $0 leq x leq 255$, where $f(0) = 0$, $f(255) = 255$ and e.g., $f(128) = 150$ (the value of $150$ might vary).
All other values should be interpolated.
So actually I want a function that is nonlinear (starts with $0$ and goes up to $255$, starting increasing fast and finishes increasing slow); opposite as a parabolic function.
What (kind of) function should I use?
functions
$endgroup$
|
show 4 more comments
$begingroup$
Suppose I have a formula
$$f(x) = x,$$
where $0 leq x leq 255$
Now I want to have a formula
$$f(x) = y,$$
where $0 leq x leq 255$, where $f(0) = 0$, $f(255) = 255$ and e.g., $f(128) = 150$ (the value of $150$ might vary).
All other values should be interpolated.
So actually I want a function that is nonlinear (starts with $0$ and goes up to $255$, starting increasing fast and finishes increasing slow); opposite as a parabolic function.
What (kind of) function should I use?
functions
$endgroup$
3
$begingroup$
So you want a function $f(x)$ such that $f(0) = 0$ , $f(128)=150$ and $f(255) = 255$?
$endgroup$
– NoChance
May 15 at 21:17
$begingroup$
Welcome to Mathematics Stack Exchange! A quick tour will enhance your experience. Here are helpful tips to write a good question and write a good answer. For equations, please refer to this MathJax tutorial.
$endgroup$
– Pantelis Sopasakis
May 15 at 21:17
2
$begingroup$
You may use a logistic function.
$endgroup$
– minori minus
May 15 at 21:18
$begingroup$
You can interpolate and get a parabolic function, I don't get what you mean by "opposite as a parabolic function".
$endgroup$
– Crostul
May 15 at 21:18
1
$begingroup$
See wolframalpha.com/input/… . Wolfram Alpha describes an arc of a parabola.
$endgroup$
– Crostul
May 15 at 21:26
|
show 4 more comments
$begingroup$
Suppose I have a formula
$$f(x) = x,$$
where $0 leq x leq 255$
Now I want to have a formula
$$f(x) = y,$$
where $0 leq x leq 255$, where $f(0) = 0$, $f(255) = 255$ and e.g., $f(128) = 150$ (the value of $150$ might vary).
All other values should be interpolated.
So actually I want a function that is nonlinear (starts with $0$ and goes up to $255$, starting increasing fast and finishes increasing slow); opposite as a parabolic function.
What (kind of) function should I use?
functions
$endgroup$
Suppose I have a formula
$$f(x) = x,$$
where $0 leq x leq 255$
Now I want to have a formula
$$f(x) = y,$$
where $0 leq x leq 255$, where $f(0) = 0$, $f(255) = 255$ and e.g., $f(128) = 150$ (the value of $150$ might vary).
All other values should be interpolated.
So actually I want a function that is nonlinear (starts with $0$ and goes up to $255$, starting increasing fast and finishes increasing slow); opposite as a parabolic function.
What (kind of) function should I use?
functions
functions
edited May 15 at 21:28
Pantelis Sopasakis
2,7791141
2,7791141
asked May 15 at 21:13
Michel KeijzersMichel Keijzers
1469
1469
3
$begingroup$
So you want a function $f(x)$ such that $f(0) = 0$ , $f(128)=150$ and $f(255) = 255$?
$endgroup$
– NoChance
May 15 at 21:17
$begingroup$
Welcome to Mathematics Stack Exchange! A quick tour will enhance your experience. Here are helpful tips to write a good question and write a good answer. For equations, please refer to this MathJax tutorial.
$endgroup$
– Pantelis Sopasakis
May 15 at 21:17
2
$begingroup$
You may use a logistic function.
$endgroup$
– minori minus
May 15 at 21:18
$begingroup$
You can interpolate and get a parabolic function, I don't get what you mean by "opposite as a parabolic function".
$endgroup$
– Crostul
May 15 at 21:18
1
$begingroup$
See wolframalpha.com/input/… . Wolfram Alpha describes an arc of a parabola.
$endgroup$
– Crostul
May 15 at 21:26
|
show 4 more comments
3
$begingroup$
So you want a function $f(x)$ such that $f(0) = 0$ , $f(128)=150$ and $f(255) = 255$?
$endgroup$
– NoChance
May 15 at 21:17
$begingroup$
Welcome to Mathematics Stack Exchange! A quick tour will enhance your experience. Here are helpful tips to write a good question and write a good answer. For equations, please refer to this MathJax tutorial.
$endgroup$
– Pantelis Sopasakis
May 15 at 21:17
2
$begingroup$
You may use a logistic function.
$endgroup$
– minori minus
May 15 at 21:18
$begingroup$
You can interpolate and get a parabolic function, I don't get what you mean by "opposite as a parabolic function".
$endgroup$
– Crostul
May 15 at 21:18
1
$begingroup$
See wolframalpha.com/input/… . Wolfram Alpha describes an arc of a parabola.
$endgroup$
– Crostul
May 15 at 21:26
3
3
$begingroup$
So you want a function $f(x)$ such that $f(0) = 0$ , $f(128)=150$ and $f(255) = 255$?
$endgroup$
– NoChance
May 15 at 21:17
$begingroup$
So you want a function $f(x)$ such that $f(0) = 0$ , $f(128)=150$ and $f(255) = 255$?
$endgroup$
– NoChance
May 15 at 21:17
$begingroup$
Welcome to Mathematics Stack Exchange! A quick tour will enhance your experience. Here are helpful tips to write a good question and write a good answer. For equations, please refer to this MathJax tutorial.
$endgroup$
– Pantelis Sopasakis
May 15 at 21:17
$begingroup$
Welcome to Mathematics Stack Exchange! A quick tour will enhance your experience. Here are helpful tips to write a good question and write a good answer. For equations, please refer to this MathJax tutorial.
$endgroup$
– Pantelis Sopasakis
May 15 at 21:17
2
2
$begingroup$
You may use a logistic function.
$endgroup$
– minori minus
May 15 at 21:18
$begingroup$
You may use a logistic function.
$endgroup$
– minori minus
May 15 at 21:18
$begingroup$
You can interpolate and get a parabolic function, I don't get what you mean by "opposite as a parabolic function".
$endgroup$
– Crostul
May 15 at 21:18
$begingroup$
You can interpolate and get a parabolic function, I don't get what you mean by "opposite as a parabolic function".
$endgroup$
– Crostul
May 15 at 21:18
1
1
$begingroup$
See wolframalpha.com/input/… . Wolfram Alpha describes an arc of a parabola.
$endgroup$
– Crostul
May 15 at 21:26
$begingroup$
See wolframalpha.com/input/… . Wolfram Alpha describes an arc of a parabola.
$endgroup$
– Crostul
May 15 at 21:26
|
show 4 more comments
3 Answers
3
active
oldest
votes
$begingroup$
WA gives $$frac10933x-11x^28128$$
https://www.wolframalpha.com/input/?i=interpolate+((0,0),(128,150)(255,255))
$endgroup$
add a comment |
$begingroup$
I think one classical example of nonlinearity could be the gamma for color correction.
Instead of using the interval $X=0 .. 255$ it is easier to work in $[0,1]$ by scaling $x=frac X255$.
Now, remark that any $x^gamma$ stays in $[0,1]$ since $0^gamma=0$ and $1^gamma=1$.
Remark: this is not exactly color correction, which is $x^1/gamma$, but this is just a convention.
So you have linearity for $gamma=1$ and non-linearity for any other value of the exponent.
Note that if you really want to work with bytes the result can be scaled back using $255timesleft(frac X255right)^gamma$
Depending of your choice of $gamma<1$ or $gamma>1$ you will get either a fast increase at the start of the interval or at the end of the interval.
Try it here (move the g cursor): https://www.desmos.com/calculator/cnc2diykyx
$endgroup$
$begingroup$
Actually, this is indeed exact the reason I use it for ... but I kind of promised the acceptance of the answer to Crostul (since he exactly answered my question), but your answer is perfect for the reason I need it for. Hope you understand.
$endgroup$
– Michel Keijzers
May 15 at 22:14
2
$begingroup$
@MichelKeijzers In that case, I'd wager there already exists a library function for precisely that purpose
$endgroup$
– Hagen von Eitzen
May 16 at 5:53
$begingroup$
Desmos seems like an excellent tool. Thanks for the tip!
$endgroup$
– Eric Duminil
May 16 at 6:34
$begingroup$
@HagenvonEitzen Probably yes, but for this so simple function I can program the one line formula.
$endgroup$
– Michel Keijzers
May 16 at 11:09
add a comment |
$begingroup$
To satisfy the requirements:
$$f(128)=150, f(255)=255$$
However, $f(0)=0$ can't be satisfied by this method. I assumed that f(1)=1, however
you can change the numbers but not use zero, otherwise, there would be no inverse.
An example of the curve looks like this Curve
I can provide more info about the derivation if you want.
$endgroup$
$begingroup$
Thanks ... Crostul gave me already a satisfactory formula, but good to know it can be derived too... I'm not fully understand the derivation, but for me it's not that needed right know... I always can search on internet how to solve matrix calculations (I had them at school long time ago, but forgotten about them meanwhile).
$endgroup$
– Michel Keijzers
May 15 at 21:40
1
$begingroup$
Thank you for your feedback. You can construct an equation of the form $f(x)=Ax^2+Bx+C$ and substitute 3 non-zero values you know x and y for. You will get a system of equations having 3 unknowns (A, B, C). You solve for theses unknowns and plug the values back into $f(x)=Ax^2+Bx+C$. Matrix calculations are optional.
$endgroup$
– NoChance
May 15 at 21:44
$begingroup$
Thanks ... that makes a lot of sense indeed, thanks for that info (very useful if in future I encounter similar problems, solving such equations even I should still be able to do that :-) ).
$endgroup$
– Michel Keijzers
May 15 at 21:47
1
$begingroup$
Thank you, I will be very happy to help.
$endgroup$
– NoChance
May 15 at 21:48
$begingroup$
Thanks (although most of my questions are in the electronics/Arduino stack exchange).
$endgroup$
– Michel Keijzers
May 15 at 21:50
add a comment |
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3 Answers
3
active
oldest
votes
3 Answers
3
active
oldest
votes
active
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active
oldest
votes
$begingroup$
WA gives $$frac10933x-11x^28128$$
https://www.wolframalpha.com/input/?i=interpolate+((0,0),(128,150)(255,255))
$endgroup$
add a comment |
$begingroup$
WA gives $$frac10933x-11x^28128$$
https://www.wolframalpha.com/input/?i=interpolate+((0,0),(128,150)(255,255))
$endgroup$
add a comment |
$begingroup$
WA gives $$frac10933x-11x^28128$$
https://www.wolframalpha.com/input/?i=interpolate+((0,0),(128,150)(255,255))
$endgroup$
WA gives $$frac10933x-11x^28128$$
https://www.wolframalpha.com/input/?i=interpolate+((0,0),(128,150)(255,255))
answered May 15 at 21:31
CrostulCrostul
28.4k22352
28.4k22352
add a comment |
add a comment |
$begingroup$
I think one classical example of nonlinearity could be the gamma for color correction.
Instead of using the interval $X=0 .. 255$ it is easier to work in $[0,1]$ by scaling $x=frac X255$.
Now, remark that any $x^gamma$ stays in $[0,1]$ since $0^gamma=0$ and $1^gamma=1$.
Remark: this is not exactly color correction, which is $x^1/gamma$, but this is just a convention.
So you have linearity for $gamma=1$ and non-linearity for any other value of the exponent.
Note that if you really want to work with bytes the result can be scaled back using $255timesleft(frac X255right)^gamma$
Depending of your choice of $gamma<1$ or $gamma>1$ you will get either a fast increase at the start of the interval or at the end of the interval.
Try it here (move the g cursor): https://www.desmos.com/calculator/cnc2diykyx
$endgroup$
$begingroup$
Actually, this is indeed exact the reason I use it for ... but I kind of promised the acceptance of the answer to Crostul (since he exactly answered my question), but your answer is perfect for the reason I need it for. Hope you understand.
$endgroup$
– Michel Keijzers
May 15 at 22:14
2
$begingroup$
@MichelKeijzers In that case, I'd wager there already exists a library function for precisely that purpose
$endgroup$
– Hagen von Eitzen
May 16 at 5:53
$begingroup$
Desmos seems like an excellent tool. Thanks for the tip!
$endgroup$
– Eric Duminil
May 16 at 6:34
$begingroup$
@HagenvonEitzen Probably yes, but for this so simple function I can program the one line formula.
$endgroup$
– Michel Keijzers
May 16 at 11:09
add a comment |
$begingroup$
I think one classical example of nonlinearity could be the gamma for color correction.
Instead of using the interval $X=0 .. 255$ it is easier to work in $[0,1]$ by scaling $x=frac X255$.
Now, remark that any $x^gamma$ stays in $[0,1]$ since $0^gamma=0$ and $1^gamma=1$.
Remark: this is not exactly color correction, which is $x^1/gamma$, but this is just a convention.
So you have linearity for $gamma=1$ and non-linearity for any other value of the exponent.
Note that if you really want to work with bytes the result can be scaled back using $255timesleft(frac X255right)^gamma$
Depending of your choice of $gamma<1$ or $gamma>1$ you will get either a fast increase at the start of the interval or at the end of the interval.
Try it here (move the g cursor): https://www.desmos.com/calculator/cnc2diykyx
$endgroup$
$begingroup$
Actually, this is indeed exact the reason I use it for ... but I kind of promised the acceptance of the answer to Crostul (since he exactly answered my question), but your answer is perfect for the reason I need it for. Hope you understand.
$endgroup$
– Michel Keijzers
May 15 at 22:14
2
$begingroup$
@MichelKeijzers In that case, I'd wager there already exists a library function for precisely that purpose
$endgroup$
– Hagen von Eitzen
May 16 at 5:53
$begingroup$
Desmos seems like an excellent tool. Thanks for the tip!
$endgroup$
– Eric Duminil
May 16 at 6:34
$begingroup$
@HagenvonEitzen Probably yes, but for this so simple function I can program the one line formula.
$endgroup$
– Michel Keijzers
May 16 at 11:09
add a comment |
$begingroup$
I think one classical example of nonlinearity could be the gamma for color correction.
Instead of using the interval $X=0 .. 255$ it is easier to work in $[0,1]$ by scaling $x=frac X255$.
Now, remark that any $x^gamma$ stays in $[0,1]$ since $0^gamma=0$ and $1^gamma=1$.
Remark: this is not exactly color correction, which is $x^1/gamma$, but this is just a convention.
So you have linearity for $gamma=1$ and non-linearity for any other value of the exponent.
Note that if you really want to work with bytes the result can be scaled back using $255timesleft(frac X255right)^gamma$
Depending of your choice of $gamma<1$ or $gamma>1$ you will get either a fast increase at the start of the interval or at the end of the interval.
Try it here (move the g cursor): https://www.desmos.com/calculator/cnc2diykyx
$endgroup$
I think one classical example of nonlinearity could be the gamma for color correction.
Instead of using the interval $X=0 .. 255$ it is easier to work in $[0,1]$ by scaling $x=frac X255$.
Now, remark that any $x^gamma$ stays in $[0,1]$ since $0^gamma=0$ and $1^gamma=1$.
Remark: this is not exactly color correction, which is $x^1/gamma$, but this is just a convention.
So you have linearity for $gamma=1$ and non-linearity for any other value of the exponent.
Note that if you really want to work with bytes the result can be scaled back using $255timesleft(frac X255right)^gamma$
Depending of your choice of $gamma<1$ or $gamma>1$ you will get either a fast increase at the start of the interval or at the end of the interval.
Try it here (move the g cursor): https://www.desmos.com/calculator/cnc2diykyx
answered May 15 at 21:59
zwimzwim
13.5k834
13.5k834
$begingroup$
Actually, this is indeed exact the reason I use it for ... but I kind of promised the acceptance of the answer to Crostul (since he exactly answered my question), but your answer is perfect for the reason I need it for. Hope you understand.
$endgroup$
– Michel Keijzers
May 15 at 22:14
2
$begingroup$
@MichelKeijzers In that case, I'd wager there already exists a library function for precisely that purpose
$endgroup$
– Hagen von Eitzen
May 16 at 5:53
$begingroup$
Desmos seems like an excellent tool. Thanks for the tip!
$endgroup$
– Eric Duminil
May 16 at 6:34
$begingroup$
@HagenvonEitzen Probably yes, but for this so simple function I can program the one line formula.
$endgroup$
– Michel Keijzers
May 16 at 11:09
add a comment |
$begingroup$
Actually, this is indeed exact the reason I use it for ... but I kind of promised the acceptance of the answer to Crostul (since he exactly answered my question), but your answer is perfect for the reason I need it for. Hope you understand.
$endgroup$
– Michel Keijzers
May 15 at 22:14
2
$begingroup$
@MichelKeijzers In that case, I'd wager there already exists a library function for precisely that purpose
$endgroup$
– Hagen von Eitzen
May 16 at 5:53
$begingroup$
Desmos seems like an excellent tool. Thanks for the tip!
$endgroup$
– Eric Duminil
May 16 at 6:34
$begingroup$
@HagenvonEitzen Probably yes, but for this so simple function I can program the one line formula.
$endgroup$
– Michel Keijzers
May 16 at 11:09
$begingroup$
Actually, this is indeed exact the reason I use it for ... but I kind of promised the acceptance of the answer to Crostul (since he exactly answered my question), but your answer is perfect for the reason I need it for. Hope you understand.
$endgroup$
– Michel Keijzers
May 15 at 22:14
$begingroup$
Actually, this is indeed exact the reason I use it for ... but I kind of promised the acceptance of the answer to Crostul (since he exactly answered my question), but your answer is perfect for the reason I need it for. Hope you understand.
$endgroup$
– Michel Keijzers
May 15 at 22:14
2
2
$begingroup$
@MichelKeijzers In that case, I'd wager there already exists a library function for precisely that purpose
$endgroup$
– Hagen von Eitzen
May 16 at 5:53
$begingroup$
@MichelKeijzers In that case, I'd wager there already exists a library function for precisely that purpose
$endgroup$
– Hagen von Eitzen
May 16 at 5:53
$begingroup$
Desmos seems like an excellent tool. Thanks for the tip!
$endgroup$
– Eric Duminil
May 16 at 6:34
$begingroup$
Desmos seems like an excellent tool. Thanks for the tip!
$endgroup$
– Eric Duminil
May 16 at 6:34
$begingroup$
@HagenvonEitzen Probably yes, but for this so simple function I can program the one line formula.
$endgroup$
– Michel Keijzers
May 16 at 11:09
$begingroup$
@HagenvonEitzen Probably yes, but for this so simple function I can program the one line formula.
$endgroup$
– Michel Keijzers
May 16 at 11:09
add a comment |
$begingroup$
To satisfy the requirements:
$$f(128)=150, f(255)=255$$
However, $f(0)=0$ can't be satisfied by this method. I assumed that f(1)=1, however
you can change the numbers but not use zero, otherwise, there would be no inverse.
An example of the curve looks like this Curve
I can provide more info about the derivation if you want.
$endgroup$
$begingroup$
Thanks ... Crostul gave me already a satisfactory formula, but good to know it can be derived too... I'm not fully understand the derivation, but for me it's not that needed right know... I always can search on internet how to solve matrix calculations (I had them at school long time ago, but forgotten about them meanwhile).
$endgroup$
– Michel Keijzers
May 15 at 21:40
1
$begingroup$
Thank you for your feedback. You can construct an equation of the form $f(x)=Ax^2+Bx+C$ and substitute 3 non-zero values you know x and y for. You will get a system of equations having 3 unknowns (A, B, C). You solve for theses unknowns and plug the values back into $f(x)=Ax^2+Bx+C$. Matrix calculations are optional.
$endgroup$
– NoChance
May 15 at 21:44
$begingroup$
Thanks ... that makes a lot of sense indeed, thanks for that info (very useful if in future I encounter similar problems, solving such equations even I should still be able to do that :-) ).
$endgroup$
– Michel Keijzers
May 15 at 21:47
1
$begingroup$
Thank you, I will be very happy to help.
$endgroup$
– NoChance
May 15 at 21:48
$begingroup$
Thanks (although most of my questions are in the electronics/Arduino stack exchange).
$endgroup$
– Michel Keijzers
May 15 at 21:50
add a comment |
$begingroup$
To satisfy the requirements:
$$f(128)=150, f(255)=255$$
However, $f(0)=0$ can't be satisfied by this method. I assumed that f(1)=1, however
you can change the numbers but not use zero, otherwise, there would be no inverse.
An example of the curve looks like this Curve
I can provide more info about the derivation if you want.
$endgroup$
$begingroup$
Thanks ... Crostul gave me already a satisfactory formula, but good to know it can be derived too... I'm not fully understand the derivation, but for me it's not that needed right know... I always can search on internet how to solve matrix calculations (I had them at school long time ago, but forgotten about them meanwhile).
$endgroup$
– Michel Keijzers
May 15 at 21:40
1
$begingroup$
Thank you for your feedback. You can construct an equation of the form $f(x)=Ax^2+Bx+C$ and substitute 3 non-zero values you know x and y for. You will get a system of equations having 3 unknowns (A, B, C). You solve for theses unknowns and plug the values back into $f(x)=Ax^2+Bx+C$. Matrix calculations are optional.
$endgroup$
– NoChance
May 15 at 21:44
$begingroup$
Thanks ... that makes a lot of sense indeed, thanks for that info (very useful if in future I encounter similar problems, solving such equations even I should still be able to do that :-) ).
$endgroup$
– Michel Keijzers
May 15 at 21:47
1
$begingroup$
Thank you, I will be very happy to help.
$endgroup$
– NoChance
May 15 at 21:48
$begingroup$
Thanks (although most of my questions are in the electronics/Arduino stack exchange).
$endgroup$
– Michel Keijzers
May 15 at 21:50
add a comment |
$begingroup$
To satisfy the requirements:
$$f(128)=150, f(255)=255$$
However, $f(0)=0$ can't be satisfied by this method. I assumed that f(1)=1, however
you can change the numbers but not use zero, otherwise, there would be no inverse.
An example of the curve looks like this Curve
I can provide more info about the derivation if you want.
$endgroup$
To satisfy the requirements:
$$f(128)=150, f(255)=255$$
However, $f(0)=0$ can't be satisfied by this method. I assumed that f(1)=1, however
you can change the numbers but not use zero, otherwise, there would be no inverse.
An example of the curve looks like this Curve
I can provide more info about the derivation if you want.
edited May 15 at 21:41
answered May 15 at 21:37
NoChanceNoChance
3,97521321
3,97521321
$begingroup$
Thanks ... Crostul gave me already a satisfactory formula, but good to know it can be derived too... I'm not fully understand the derivation, but for me it's not that needed right know... I always can search on internet how to solve matrix calculations (I had them at school long time ago, but forgotten about them meanwhile).
$endgroup$
– Michel Keijzers
May 15 at 21:40
1
$begingroup$
Thank you for your feedback. You can construct an equation of the form $f(x)=Ax^2+Bx+C$ and substitute 3 non-zero values you know x and y for. You will get a system of equations having 3 unknowns (A, B, C). You solve for theses unknowns and plug the values back into $f(x)=Ax^2+Bx+C$. Matrix calculations are optional.
$endgroup$
– NoChance
May 15 at 21:44
$begingroup$
Thanks ... that makes a lot of sense indeed, thanks for that info (very useful if in future I encounter similar problems, solving such equations even I should still be able to do that :-) ).
$endgroup$
– Michel Keijzers
May 15 at 21:47
1
$begingroup$
Thank you, I will be very happy to help.
$endgroup$
– NoChance
May 15 at 21:48
$begingroup$
Thanks (although most of my questions are in the electronics/Arduino stack exchange).
$endgroup$
– Michel Keijzers
May 15 at 21:50
add a comment |
$begingroup$
Thanks ... Crostul gave me already a satisfactory formula, but good to know it can be derived too... I'm not fully understand the derivation, but for me it's not that needed right know... I always can search on internet how to solve matrix calculations (I had them at school long time ago, but forgotten about them meanwhile).
$endgroup$
– Michel Keijzers
May 15 at 21:40
1
$begingroup$
Thank you for your feedback. You can construct an equation of the form $f(x)=Ax^2+Bx+C$ and substitute 3 non-zero values you know x and y for. You will get a system of equations having 3 unknowns (A, B, C). You solve for theses unknowns and plug the values back into $f(x)=Ax^2+Bx+C$. Matrix calculations are optional.
$endgroup$
– NoChance
May 15 at 21:44
$begingroup$
Thanks ... that makes a lot of sense indeed, thanks for that info (very useful if in future I encounter similar problems, solving such equations even I should still be able to do that :-) ).
$endgroup$
– Michel Keijzers
May 15 at 21:47
1
$begingroup$
Thank you, I will be very happy to help.
$endgroup$
– NoChance
May 15 at 21:48
$begingroup$
Thanks (although most of my questions are in the electronics/Arduino stack exchange).
$endgroup$
– Michel Keijzers
May 15 at 21:50
$begingroup$
Thanks ... Crostul gave me already a satisfactory formula, but good to know it can be derived too... I'm not fully understand the derivation, but for me it's not that needed right know... I always can search on internet how to solve matrix calculations (I had them at school long time ago, but forgotten about them meanwhile).
$endgroup$
– Michel Keijzers
May 15 at 21:40
$begingroup$
Thanks ... Crostul gave me already a satisfactory formula, but good to know it can be derived too... I'm not fully understand the derivation, but for me it's not that needed right know... I always can search on internet how to solve matrix calculations (I had them at school long time ago, but forgotten about them meanwhile).
$endgroup$
– Michel Keijzers
May 15 at 21:40
1
1
$begingroup$
Thank you for your feedback. You can construct an equation of the form $f(x)=Ax^2+Bx+C$ and substitute 3 non-zero values you know x and y for. You will get a system of equations having 3 unknowns (A, B, C). You solve for theses unknowns and plug the values back into $f(x)=Ax^2+Bx+C$. Matrix calculations are optional.
$endgroup$
– NoChance
May 15 at 21:44
$begingroup$
Thank you for your feedback. You can construct an equation of the form $f(x)=Ax^2+Bx+C$ and substitute 3 non-zero values you know x and y for. You will get a system of equations having 3 unknowns (A, B, C). You solve for theses unknowns and plug the values back into $f(x)=Ax^2+Bx+C$. Matrix calculations are optional.
$endgroup$
– NoChance
May 15 at 21:44
$begingroup$
Thanks ... that makes a lot of sense indeed, thanks for that info (very useful if in future I encounter similar problems, solving such equations even I should still be able to do that :-) ).
$endgroup$
– Michel Keijzers
May 15 at 21:47
$begingroup$
Thanks ... that makes a lot of sense indeed, thanks for that info (very useful if in future I encounter similar problems, solving such equations even I should still be able to do that :-) ).
$endgroup$
– Michel Keijzers
May 15 at 21:47
1
1
$begingroup$
Thank you, I will be very happy to help.
$endgroup$
– NoChance
May 15 at 21:48
$begingroup$
Thank you, I will be very happy to help.
$endgroup$
– NoChance
May 15 at 21:48
$begingroup$
Thanks (although most of my questions are in the electronics/Arduino stack exchange).
$endgroup$
– Michel Keijzers
May 15 at 21:50
$begingroup$
Thanks (although most of my questions are in the electronics/Arduino stack exchange).
$endgroup$
– Michel Keijzers
May 15 at 21:50
add a comment |
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$begingroup$
So you want a function $f(x)$ such that $f(0) = 0$ , $f(128)=150$ and $f(255) = 255$?
$endgroup$
– NoChance
May 15 at 21:17
$begingroup$
Welcome to Mathematics Stack Exchange! A quick tour will enhance your experience. Here are helpful tips to write a good question and write a good answer. For equations, please refer to this MathJax tutorial.
$endgroup$
– Pantelis Sopasakis
May 15 at 21:17
2
$begingroup$
You may use a logistic function.
$endgroup$
– minori minus
May 15 at 21:18
$begingroup$
You can interpolate and get a parabolic function, I don't get what you mean by "opposite as a parabolic function".
$endgroup$
– Crostul
May 15 at 21:18
1
$begingroup$
See wolframalpha.com/input/… . Wolfram Alpha describes an arc of a parabola.
$endgroup$
– Crostul
May 15 at 21:26