Add const declaration to pointers to data only read.

src/zaxis.c

@@ -1553,7 +1553,7 @@ zaxisCompareP(zaxis_t *z1, zaxis_t *z2)
   anyPresent |= present;
   if (!diff && present)
     {
-      double *p = z1->vals, *q = z2->vals;
+      const double *p = z1->vals, *q = z2->vals;
       for (int i = 0; i < size; i++)
         diff |= IS_NOT_EQUAL(p[i], q[i]);
     }
@@ -1563,7 +1563,7 @@ zaxisCompareP(zaxis_t *z1, zaxis_t *z2)
   anyPresent |= present;
   if (!diff && present)
     {
-      double *p = z1->lbounds, *q = z2->lbounds;
+      const double *p = z1->lbounds, *q = z2->lbounds;
       for (int i = 0; i < size; i++)
         diff |= IS_NOT_EQUAL(p[i], q[i]);
     }
@@ -1573,7 +1573,7 @@ zaxisCompareP(zaxis_t *z1, zaxis_t *z2)
   anyPresent |= present;
   if (!diff && present)
     {
-      double *p = z1->ubounds, *q = z2->ubounds;
+      const double *p = z1->ubounds, *q = z2->ubounds;
       for (int i = 0; i < size; ++i)
         diff |= IS_NOT_EQUAL(p[i], q[i]);
     }
@@ -1583,7 +1583,7 @@ zaxisCompareP(zaxis_t *z1, zaxis_t *z2)
   anyPresent |= present;
   if (!diff && present)
     {
-      double *p = z1->weights, *q = z2->weights;
+      const double *p = z1->weights, *q = z2->weights;
       for (int i = 0; i < size; ++i)
         diff |= IS_NOT_EQUAL(p[i], q[i]);
     }
@@ -1594,7 +1594,7 @@ zaxisCompareP(zaxis_t *z1, zaxis_t *z2)
     {
       int vctsize = z1->vctsize;
       xassert(vctsize);
-      double *p = z1->vct, *q = z2->vct;
+      const double *p = z1->vct, *q = z2->vct;
       for (int i = 0; i < vctsize; ++i)
         diff |= IS_NOT_EQUAL(p[i], q[i]);
     }