my $model = "c*theta*hˆ(1+psi)=(1-alpha)*y;\n1 = beta*(c/c(+1)*alpha*y(+1)/k+(1-delta));\ny = a*(k(-1)ˆalpha)*(hˆ(1-alpha));\nk = y-c+(1-delta)*k(-1);\nln(a) = rho*ln(a(-1))+ e;\n";

my @varlist = ('y','c','k','a','h');

my ($replacement,$search_string);
foreach my $var (@varlist){
      $search_string = quotemeta($var);
      $replacement = "$steady_states{$var}*exp(${var})";
      $model =~ s/(\W)$search_string(\W)/$1($replacement)$2/g;
      $model =~ s/^$search_string(\W)/($replacement)$1/g;
      $model =~ s/exp\($search_string(\))+(\([\+\-]1\))/exp($search_string$2$1)/g;
    }

print $model;