[Rd] Use d0 instead of _8 in ppr.f ?

[Suharto Anggono Suharto Anggono]

SVN revision 89917 adds "_8" to some numbers in src/library/stats/src/ppr.f , with message
flang-22 wants explicit "double" / "8-bit float" constants

How about using "d0" instead? It is more consistent within the file and a little more portable. The number doesn't have to be equal to the number of bytes, 8.

Here is a patch that replaces "_8" with "d0".

--- ppr.f	2026-04-29 09:39:32.145702763 +0000
+++ ppr_d0.f	2026-04-29 09:39:32.268715531 +0000
@@ -842,9 +842,9 @@
 
       data df, gcvpen, ismethod, trace /4d0, 1d0, 0, .false./
       data ifl,maxit, conv, mitone, cutmin, fdel
-     &    / 6,  20,  .005_8,   20,   0.1_8, 0.02_8 /
+     &    / 6,  20,  .005d0,   20,   0.1d0, 0.02d0 /
       data span,alpha, big,   cjeps,  mitcj, lf
-     &    / 0.0, 0.0, 1.0e20, 0.001_8,   1,   2 /
+     &    / 0.0, 0.0, 1.0e20, 0.001d0,   1,   2 /
       end
 
       subroutine setppr(span1, alpha1, optlevel, ism, df1, gcvpen1)
@@ -1259,7 +1259,7 @@
       common /spans/ spans /consts/ big,sml,eps
 
       data spans,               big,  sml,  eps
-     &  /0.05_8, 0.2_8, 0.5, 1.0e20,1.0e-7,1.0e-3/
+     &  /0.05d0, 0.2d0, 0.5, 1.0e20,1.0e-7,1.0e-3/
       end
 c---------------------------------------------------------------
 c
@@ -1384,7 +1384,7 @@
 c     tol for 'spar' estimation:
       param(3) = 1d-2
 c     'eps' (~= 2^-12 = sqrt(2^-24) ?= sqrt(machine eps)) in ./sbart.c :
-      param(4) = .000244_8
+      param(4) = .000244d0
 
       ier = 1
       call rbart(gcvpen,df1,dx,dy,dw,0.0d0,n,knot,nk,coef,dsmo,lev,


This is an alternative that uses "d" for all "double precision".

--- ppr.f	2026-04-29 09:39:32.145702763 +0000
+++ ppr_d0_all.f	2026-04-29 09:39:32.291717918 +0000
@@ -842,9 +842,9 @@
 
       data df, gcvpen, ismethod, trace /4d0, 1d0, 0, .false./
       data ifl,maxit, conv, mitone, cutmin, fdel
-     &    / 6,  20,  .005_8,   20,   0.1_8, 0.02_8 /
+     &    / 6,  20,  .005d0,   20,   0.1d0, 0.02d0 /
       data span,alpha, big,   cjeps,  mitcj, lf
-     &    / 0.0, 0.0, 1.0e20, 0.001_8,   1,   2 /
+     &    / 0d0, 0d0, 1.0d20, 0.001d0,   1,   2 /
       end
 
       subroutine setppr(span1, alpha1, optlevel, ism, df1, gcvpen1)
@@ -1258,8 +1258,8 @@
       double precision spans(3),    big,sml,eps
       common /spans/ spans /consts/ big,sml,eps
 
-      data spans,               big,  sml,  eps
-     &  /0.05_8, 0.2_8, 0.5, 1.0e20,1.0e-7,1.0e-3/
+      data spans,                 big,  sml,  eps
+     &  /0.05d0, 0.2d0, 0.5d0, 1.0d20,1.0d-7,1.0d-3/
       end
 c---------------------------------------------------------------
 c
@@ -1384,7 +1384,7 @@
 c     tol for 'spar' estimation:
       param(3) = 1d-2
 c     'eps' (~= 2^-12 = sqrt(2^-24) ?= sqrt(machine eps)) in ./sbart.c :
-      param(4) = .000244_8
+      param(4) = .000244d0
 
       ier = 1
       call rbart(gcvpen,df1,dx,dy,dw,0.0d0,n,knot,nk,coef,dsmo,lev,