**⚠️ Warning: This is a draft ⚠️**

This means it might contain formatting issues, incorrect code, conceptual problems, or other severe issues.

If you want to help to improve and eventually enable this page, please fork RosettaGit's repository and open a merge request on GitHub.

==a REXX version of a REXX version== This REXX version is a re-write of version 2 of the REXX entry, with: ::* added the required comment so that this REXX version would execute on VM/CMS and MVS/TSO ::* aligned indentation for all '''do-end''' blocks (and encapsulated statements) ::* elided distracting superfluous zeros in integers ::* elided superfluous decimal points in integers ::* elides the superfluous and distracting use of concatenation ('''││''') ::* a unique symbol instead of a null literal for a special case ::* aligns the data points and results in the output ::* adds whitespace to make arithmetic computations more perusable ::* eschews title-case capitalizations ::* maintains the same line for the '''then''' clause and the '''if''' clause (no split statements) ::* uses indentations for all REXX statements in the function ::* has the result on the same line as the input (data points) ::* a different quoted literal style (for easier reading of multiple literals on the same clause) ::* REXX variables to hold long literals that would otherwise cause excessive wide REXX statements ::* a comma (instead of a slash) to separate the '''x y''' coördinates of the data points. ::* elides superfluous '''do-end''' block structures; less clutter, easier to read ::* added more whitespace within some REXX statements and the REXX program's output ::* tests all data possibilities (for showing all the tested non-intersecting conditions) ::* for viewing the calculation in its entirity, all program logic was kept within single viewable screen

{{trans|REXX (version 2)}}

```
/*REXX program finds (possibly) the intersection of two lines (with diagnostic errors).*/
say iSect( 4 0 6 10 0 3 10 7 )
say iSect( 0 0 0 10 0 3 10 7 )
say iSect( 0 0 0 10 0 3 10 7 )
say iSect( 0 0 0 1 1 0 1 7 )
say iSect( 0 0 0 0 0 3 10 7 )
say iSect( 0 0 3 3 0 0 6 6 )
say iSect( 0 0 3 3 0 1 6 7 )
say iSect( 0 0 3 3 8 8 8 8 )
exit /* ═══a═══ ═══b═══ ═══c═══ ═══c═══ stick a fork in it, we're all done. */
/*──────────────────────────────────────────────────────────────────────────────────────*/
iSect: procedure; parse arg xa ya xb yb xc yc xd yd /*optain args from invocation. */
$=. /*the intersection or error msg.*/
if xa=xb then do; k1=. /*the slope is infinite. */
x1=xa /*the X's intersection is XA */
if ya=yb then $= 'points A and B are identical'
end /* [↑] AB is a vertical line. */
else do; k1=(yb-ya) / (xb-xa) /*compute the slope of AB */
d1=ya - k1 * xa /*calc. intersection with Y axis*/
end /* [↑] AB isn't a vertical line*/
if xc=xd then do; k2=. /*the slope is infinite. */
x2=xc /*the C's intersection is XC */
if yc=yd then $= 'points C and D are identical'
end /* [↑] CD is a vertical line. */
else do; k2=(yd-yc) / (xd-xc) /*compute the slope of CD */
d2=yc - k2 * xc /*calc. intersection with Y axis*/
end /* [↑] CD isn't a vertical line*/
@ident= 'lines AB and CD are identical' /*literal to help shorten a line*/
@paral= 'lines AB and CD are parallel' /* " " " " " " */
/* [↓] no special case so far···*/
if $=. then if k1=. then if k2=. then if x1=x2 then $=@ident /*identical. */
else $=@paral /*parallel. */
else do; x=x1 /*use X1 */
y=k2 * x + d2 /*Y from CD */
end
else if k2=. then do; x=x2 /*X from CD */
y=k1 * x + d1 /*Y from AB */
end
else if k1=k2 then if d1=d2 then $= @ident
else $= @paral
else do; x=(d2-d1) / (k1-k2)
y=k1 * x + d1
end /* [↑] normal*/
if $=. then $= 'intersection is at (' || x","y')' /*$ ¬defined?*/
@ = left( 'a=('xa","ya')', 12) left( 'b=('xb","yb')', 12), /*whitespace.*/
left( 'c=('xc","yc')', 12) left( 'd=('xd","yd')', 12) /* " */
return left(@, max(51, length(@) ) ) ' ───► ' $ /*return str.*/
```

{{out|output|text= when using the default inputs:}}

```
a=(4,0) b=(6,10) c=(0,3) d=(10,7) ───► intersection is at (5,5)
a=(0,0) b=(0,10) c=(0,3) d=(10,7) ───► intersection is at (0,3)
a=(0,0) b=(0,10) c=(0,3) d=(10,7) ───► intersection is at (0,3)
a=(0,0) b=(0,1) c=(1,0) d=(1,7) ───► lines AB and CD are parallel
a=(0,0) b=(0,0) c=(0,3) d=(10,7) ───► points A and B are identical
a=(0,0) b=(3,3) c=(0,0) d=(6,6) ───► lines AB and CD are identical
a=(0,0) b=(3,3) c=(0,1) d=(6,7) ───► lines AB and CD are parallel
a=(0,0) b=(3,3) c=(8,8) d=(8,8) ───► points C and D are identical
```

### ========================================================================================

: If I were to translate many of the Rexx programs of GS to my liking I'd be busy for months.
::* Here is the Rexx program as I wrote it in my style:::*

http://rosettacode.org/wiki/Find_the_intersection_of_two_lines#version_2
::* Any opinions from any peers? --[[User:Walterpachl|Walterpachl]] ([[User talk:Walterpachl|talk]]) 06:01, 19 May 2017 (UTC)

::: There is no reason to take it personally. It wasn't meant as a criticism, it is just another version in a different style, albeit a fair number of (style) differences. __Everybody's__ code can be improved (as least, the style can be changed). In this case, I elided a few superfluous statements, which, in my opinion, didn't add anything to the REXX program or make it easier to understand/peruse. I didn't appreciate your style of capitalization, misaligned DO-END statements (and the intervening/encapsulating REXX statements), split IF-THEN clauses, and much more. But, that's only my opinion and preferences, I merely added a version that I found easier to read and understand (and I hoped others will appreciate this version), and I also removed superfluous DO-END blocks and such. Note that this re-written REXX version was added in the ''discussion'' section, not on the ''page'' section so as to not clutter up the main page. I found that that particular REXX version was so difficult to follow and understand (the IF logic) with all the multiple misaligned DO-END and compound IF THEN-ELSE statements. The version (above) that I re-wrote speaks to style and understandability. There are many styles to write REXX programs in, and this is just one of them. Nobody's style is everybody's cup of tea. -- [[User:Gerard Schildberger|Gerard Schildberger]] ([[User talk:Gerard Schildberger|talk]]) 08:22, 19 May 2017 (UTC)

:::: The only thing I liked about this variation is the presentation of the result. :::: The a= etc. should be A= etc. to be consistent. :::: I dislike that the variation can no longer be used with ooRexx :-( :::: and i cannot appreciate the landscape formatting! :::: But let's agree that our taste as far as formatting is concerned is vastly different. :::: And I added commentary to my version. --[[User:Walterpachl|Walterpachl]] ([[User talk:Walterpachl|talk]]) 09:29, 19 May 2017 (UTC)