# [ncl-talk] ispan for floating steps

Mary Haley haley at ucar.edu
Tue Oct 13 14:01:38 MDT 2015

```There's an undocumented build-in function called "testspan" that may also
do what you want.

It's never been made public and it is *not* guaranteed to live forever, so
use at your own risk.

These three statements should give you the same set of values:

ilat = ispan(-360, 360,   5)   * 0.25

flat = fspan( -90,  90, 145)

lat  = testspan(  -90,  90,   1.25)

The next question is probably going to be: "why isn't this public"?

The answer is, "I don't remember".  I think it has something to do with
precision accuracy that can potentially cause a problem. Here's an example
of where you would get different values, with a slight change in precision:

f1 = testspan(1,9.999999,3)   ; 1,4,7
f2 = testspan(1,9.9999999,3)  ; 1,4,7,10

If you add a "d" to make the second argument a double, then you get better
results:

d1 = testspan(1,9.999999d,3)   ; 1,4,7
d2 = testspan(1,9.9999999d,3)  ; 1,4,7

--Mary

--Mary

On Tue, Oct 13, 2015 at 6:54 AM, Carl Schreck <cjschrec at ncsu.edu> wrote:

> This is a feature I'd wanted too, so I wrote a simple little function to
> do it (attached). cspan (for Carl's span, because I couldn't think of
> anything more descriptive).
>
>    Carl
>
> On Fri, Oct 9, 2015 at 9:58 AM, Dennis Shea <shea at ucar.edu> wrote:
>
>> Please see 'fspan'
>>
>> xlow = 1e-7
>> xhi   = 4e-05
>> xinc = 1e-7
>> nn   = toint((xhi-xlow)/xinc)+1
>>
>> x = fspan(xlow, xhi, nn)
>>
>> ====
>> *you* can create your own function
>>
>> function myspan(xlow, xhi, xinc)
>>
>> that will return  the values
>>
>> On Fri, Oct 9, 2015 at 6:55 AM, Ahmad Farsyud <a.farsyud at gmail.com>
>> wrote:
>> > Hallo,
>> >
>> > Is there any solution to execute the following command:
>> >
>> > ncl 0> x= ispan (1e-7,4e-5,1e-7)
>> > fatal:ispan: arguments must be of an integral type, can't continue
>> > fatal:["Execute.c":8573]:Execute: Error occurred at or near line 0
>> >
>> > Thanks
>> >
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>
>
>
> --
>
> <http://www.cicsnc.org/>
> <http://www.researcherid.com/rid/B-8711-2011>
> * Cyclone <http://www.cyclonecenter.org/>*Center.org
> <http://www.cyclonecenter.org/>  *Carl J. Schreck III, PhD*
> *Research Associate*
> Cooperative Institute for Climate and Satellites NC (CICS-NC)
> <http://www.cicsnc.org/> /
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