Index: /issm/trunk-jpl/externalpackages/petsc/install-3.15-mac-arm.sh
===================================================================
--- /issm/trunk-jpl/externalpackages/petsc/install-3.15-mac-arm.sh	(revision 26379)
+++ /issm/trunk-jpl/externalpackages/petsc/install-3.15-mac-arm.sh	(revision 26379)
@@ -0,0 +1,56 @@
+#!/bin/bash
+set -eu
+
+
+## Constants
+VER="3.15.2"
+
+# Download source
+$ISSM_DIR/scripts/DownloadExternalPackage.sh "https://ftp.mcs.anl.gov/pub/petsc/release-snapshots/petsc-lite-${VER}.tar.gz" "petsc-${VER}.tar.gz"
+
+# Unpack source
+tar -zxvf petsc-${VER}.tar.gz
+
+# Cleanup
+rm -rf install src
+mkdir install src
+
+# Move source to 'src' directory
+mv petsc-${VER}/* src/
+rm -rf petsc-${VER}
+
+# Configure
+#
+# NOTE:
+# - Added -fallow-argument-mismatch to FFLAGS in order to clear,
+#
+#		error: The Fortran compiler gfortran will not compile files that call 
+#		the same routine with arguments of different types.
+#
+#	for gfortran 10 or later (may need to remove it for earlier versions).
+# - Added -Wno-error=implicit-function-declaration to CFLAGS for Clang >= 12. 
+#	(may need to remove it for earlier versions not using the C99 standard).
+#
+cd src
+./config/configure.py \
+	--prefix="${ISSM_DIR}/externalpackages/petsc/install" \
+	--PETSC_DIR="${ISSM_DIR}/externalpackages/petsc/src" \
+	--CFLAGS="-Wno-error=implicit-function-declaration" \
+	--FFLAGS="-fallow-argument-mismatch" \
+	--LDFLAGS="-Wl,-no_compact_unwind" \
+	--with-debugging=0 \
+	--with-valgrind=0 \
+	--with-x=0 \
+	--with-ssl=0 \
+	--with-pic=1 \
+	--download-fblaslapack=1 \
+	--download-mpich=1 \
+	--download-metis=1 \
+	--download-parmetis=1 \
+	--download-scalapack=1 \
+	--download-mumps=1 \
+	--download-zlib=1 
+
+# Compile and install
+make
+make install