linear function with exponential decay ... i think

[ugalee]

I have this linear equation that I would like to be a declining curve that accelerates in the beginning and flattens out and never goes below .5

1-b4/b5

Can you help out?

mike

[MrShorty]

I'm sure we can, but there isn't much to go on.

The standard exponential decay function is y=A*exp(kx) [k<0]. The y intercept is A and there is a horizontal asymptote at y=0.

To shift it up to 0.5, add 0.5 to the standard equation y=0.5+A*exp(kx). This will have a y intercept at A+0.5 and a horizontal asymptote at y=0.5. k controls the rate of decay.

Provide values for A and k, and you should get the generic behavior you describe.