Merge branch 'bugfix_issue_2615' of https://github.com/stan-dev/math into bugfix_issue_2615

Author: Yi Zhang

stan/math/prim/fun/matrix_exp_2x2.hpp

@@ -51,7 +51,7 @@ matrix_exp_2x2(const EigMat& A) {
   if (B.hasNaN()) {
     return matrix_exp_pade(A);
   } else {
-    return B / delta;    
+    return B / delta;
   }
 }
 

test/unit/math/prim/fun/matrix_exp_2x2_test.cpp

@@ -24,7 +24,7 @@ TEST(MathMatrixPrimMat, matrix_exp_2x2_2x2_2) {
 TEST(MathMatrixPrimMat, matrix_exp_2x2_2x2_overflow) {
   // example from issue https://github.com/stan-dev/math/issues/2615
   Eigen::Matrix<double, Eigen::Dynamic, Eigen::Dynamic> m1(2, 2), m2(2, 2);
-  m1 << -3.3228,0.533302,1.2242,-4.04844;
+  m1 << -3.3228, 0.533302, 1.2242, -4.04844;
   double t = 800.0;
   m2 << 0.0, 0.0, 0.0, 0.0;
   EXPECT_MATRIX_FLOAT_EQ(m2, stan::math::matrix_exp_2x2(m1 * t));