inverse function command

[jonmoore]

(08-03-2022 06:20 PM)Albert Chan Wrote:  

(08-03-2022 05:26 PM)jonmoore Wrote:  BTW it's not a -45 degree rotation, it's a reflection.

That's what the sign, −f(x) is for.
Plots gives points (x,-y). Rotate calculator 90°, we have points (y,x)

But you're forgetting that the 48 series of calculators doesn't understand negated f(x) notation. e.g. If you input 'f(x)=2*x+3' and input the command DEF, this automatically gets translated to the RPL statement:

<< -> X '2*x+3' >>

However, if you input '-f(x)=2*x+3' and attempt to DEF that statement you get an invalid definition. This is the reason that Bill Wickes had to devise a workaround for Donald LaTorre's books.

My post dealt very specifically with the 48G series of calculators but the same invalid definition error applies to the 50g (and other RPL calculators) too.

Other graphing calculators may or may not work more gracefully out of the box with inverse notation but not HP's RPL calculators.