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Topic: Graph cant show my simple function

I have a function: f(x)=(phi^x - (1-phi)^x)/sqrt(5).
where phi is: (1+sqrt(5))/2 , (This is "The Golden Ratio").
x goes from -10 to 10 in steps of 1.
The function describes the Fibonacci numbers in terms of x, where x is the Nth number in the Fibonacci-series.
My x-axis goes from -10 to 10, my y-axis from -10 to 10 (Standard Zoom).
The graph is NOT shown.
But when I zoom out, to about 10 times, it shows a graph, but only a part of the graph (depending on the zoom).

I have tried to make sqrt(5) a constant: 2.236068
and phi a constant: 1.618034, and x range from 1 to 10, in steps of 1
(Without steps, the graph dosent show at any zoom level).
Nothing works!  What is wrong??

I have attached my "Fibonacci-tal.grf" file.

Re: Graph cant show my simple function

Hello, Finn:

Began playing with your issue, by constructing my grf from the text of your description of f(x) and phi --- and discovered this: in the "Edit Function" form, under "Graph properties", change the "Draw type" from "Automatic" to "Dots" or "Lines". Seems "Automatic" does not presently reconcile how to graphically render these discrete values. Perhaps Ivan can weigh in on this too.

Cheers,
Henry

Re: Graph cant show my simple function

When Draw type is Automatic the Steps is only a suggestion and Graph will often add additional points. If you set Draw type to Dots or Lines the Steps are fixed. In this case where From is -10 and To is 10 you probably want Steps to be 11, which will give a step size of 1.

Re: Graph cant show my simple function

Thanks to Henry and Ivan..

I still have a problem, when I zoom out or in. The graph dosen't show all values. Sometimes it dissapears.

When "Draw type" is Automatic, and "Step" is 11, I get the most values, but still I can't zoom properly.

I use "Graph version 4.4.2 on Windows 7, 64-bit.

Venlig hilsen: Finn Jørgensen

Re: Graph cant show my simple function

... When I use "Line type" straight line, and "Draw type" Line, with Steps 1, it works all right.
I was trying "Line type" dots, and "Draw type" dots. It did'nt work.

Thanks....  Problem solved !!