tabvar
01-26-2020, 05:46 PM
Post: #1
 lrdheat Senior Member Posts: 526 Joined: Feb 2014
tabvar
On version from 01 21 2020, tabvar is producing unexpected results on my G2. It seems to want to start a table with zero as upposed to negative infinity. Even if I do tabvar(x^2,x,-3,3), the result table will start with x=0. Other more complex functions also produce similar unexpected results. Am I doing something incorrectly?
01-26-2020, 06:15 PM
Post: #2
 Wes Loewer Member Posts: 212 Joined: Jan 2014
RE: tabvar
The tabvar command recognizes functions with odd and even symmetry and does not display the "redundant" values x<0. Try a non-symmetric function (or even just non-symmetric min/max values) and see if it gives you what you were expecting.
01-26-2020, 07:56 PM
Post: #3
 lrdheat Senior Member Posts: 526 Joined: Feb 2014
RE: tabvar
It seems as if tabvar, in a table type form, had found zeros for f(x), f’(x), f”(x), associated y values, and if f(x) was increasing or decreasing in earlier renditions. Am I thinking of a different command?
01-27-2020, 06:52 PM (This post was last modified: 01-27-2020 07:17 PM by Wes Loewer.)
Post: #4
 Wes Loewer Member Posts: 212 Joined: Jan 2014
RE: tabvar
(01-26-2020 07:56 PM)lrdheat Wrote:  It seems as if tabvar, in a table type form, had found zeros for f(x), f’(x), f”(x), associated y values, and if f(x) was increasing or decreasing in earlier renditions. Am I thinking of a different command?

Yes, that's still what it does on mine. What is it showing for you?

For example:

Are you getting something different?

Edit: It shows zeros for f’(x) and f”(x), but not f(x). I don't think this command ever did that.
01-27-2020, 07:23 PM
Post: #5
 Wes Loewer Member Posts: 212 Joined: Jan 2014
RE: tabvar
A better example is tabvar(e^x*(x-1),x)
01-28-2020, 03:02 AM
Post: #6
 lrdheat Senior Member Posts: 526 Joined: Feb 2014
RE: tabvar
I understand now. I had not tried even symmetric functions, and did not realize that for those cases, x<0 is not shown in the table, even if I ask for a range of, say, -4 to 4.
01-28-2020, 03:17 AM
Post: #7
 lrdheat Senior Member Posts: 526 Joined: Feb 2014
RE: tabvar
Try (e^(2*x))*3*x, x,-10,10 Before I hit enter from the terminal display, it shows y’=0 for x=.5). When I hit enter, the resulting table does not show an entry for y’=0. Why is this? Is this expected?
01-28-2020, 03:33 AM
Post: #8
 Wes Loewer Member Posts: 212 Joined: Jan 2014
RE: tabvar
(01-28-2020 03:17 AM)lrdheat Wrote:  Try (e^(2*x))*3*x, x,-10,10 Before I hit enter from the terminal display, it shows y’=0 for x=.5). When I hit enter, the resulting table does not show an entry for y’=0. Why is this? Is this expected?

The resulting matrix is too large to show in the history, but if you tap on the matrix and then select "Show" you should be able to see the whole thing by dragging back and forth. You should be able to see the y'=0 column at x=-1/2
01-28-2020, 04:53 AM
Post: #9
 lrdheat Senior Member Posts: 526 Joined: Feb 2014
RE: tabvar
Oh wow! Thanks! I had no idea. Love it!
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