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correctly fix invalid read from pvoc array #16

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correctly fix invalid read from pvoc array #16

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4 changes: 2 additions & 2 deletions np1.c
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Original file line number Diff line number Diff line change
Expand Up @@ -27,7 +27,7 @@ logical vbflag;
const integer r50wal = 36852;

/* System generated locals */
volatile integer ret_val, i__1, i__2;
integer ret_val, i__1, i__2;

/* Local variables */
integer i, j, adj;
Expand Down Expand Up @@ -55,7 +55,7 @@ logical vbflag;
pv_1.p2 = 0;

buzlnt = 20;
prplnt = 48;
prplnt = 45;
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@Jan200101 Jan200101 Feb 18, 2026

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Checked through everything again to confirm that this is the correct fix:

PRPLNT is also defined as 48 in the original Fortran code while PVOC is an array with only 45 entries resulting in out of bounds access.

The issue only turned fatal once optimizations were turned on and the C compiler turned the Undefined Behavior into a reason to do horrible stuff.

dirlnt = 75;
/* SPARSE, PAGE 8 */

Expand Down