sub mat4_write
{
# Variable name.
my $name = shift;

# Number of rows.
my $m = shift;

# Number of columns.
my $n = shift;

# Matrix elements in column major layout, this is the native
# Matlab storage layout for matrices.
my @a = splice (@_, 0, $m * $n);

# File handle.
my $h = shift;

# use binnary-mode:
binmode($h);

# Type flag.
my $type = $mat4_type;

# No imaginary part.
my $imag = 0;

# Length of variable name including terminating null character.
my $len = length ($name) + 1;

# Encode and print matrix.
print ($h pack ('l5Z*d*', $type, $m, $n, $imag, $len, $name, @a));
}