Math Is Fun Forum

thing2b

Member

Registered: 2007-04-10

Posts: 1

Creating an equation

I am trying to create an equation to use in a computer program. The aim is to find the value of Z, if the values of X and Y are known.

The Z value is going to be used to order some data, so the range does not matter.

I would like Z to increase as X and the result of the Y EQUATION increase.

The Y EQUATION needs to be able to be able to fit the following:
- When Y is between 30 and 40, the result of the Y EQUATION needs to be at its highest.
- When Y is at 1, the result of the Y EQUATION needs to be roughly a quater of its highest possible value.
- When Y is at 200, the result of the Y EQUATION needs to be roughly a quater of its highest possible value.
- No result of the Y EQUATION should be less than or equal to 0 when Y is greater than 0

Any help would be a godsend.
Paul

javacodeman

Member

Registered: 2007-04-04

Posts: 9

Re: Creating an equation

I am trying to create an equation to use in a computer program. The aim is to find the value of Z, if the values of X and Y are known.

The Z value is going to be used to order some data, so the range does not matter.

I would like Z to increase as X and the result of the Y EQUATION increase.

The Y EQUATION needs to be able to be able to fit the following:
- When Y is between 30 and 40, the result of the Y EQUATION needs to be at its highest.
- When Y is at 1, the result of the Y EQUATION needs to be roughly a quater of its highest possible value.
- When Y is at 200, the result of the Y EQUATION needs to be roughly a quater of its highest possible value.
- No result of the Y EQUATION should be less than or equal to 0 when Y is greater than 0

Any help would be a godsend.
Paul

I am assuming that you mean that "When X is between 30 and 40, Y needs to be at a its highest" and so forth?

John E. Franklin

Member

Registered: 2005-08-29

Posts: 3,588

Re: Creating an equation

I got an equation for you that is fairly decent.
You might want to tweek it up a little.

y = -.99 + 1.35 ^ (1/(1 + (2.6 - x^0.25)^2))

Oops, the max is in the forties for that one.

Try this one instead.

y = -.99 + 2.55 ^ (1/(1 + (2.43 - (x+1)^0.25)^2))

Last edited by John E. Franklin (2007-04-11 16:21:05)

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