These two should be equivalent....

matapp.cpp

        auto translationMat = glm::translate (
                                  glm::mat4 (1.0),
                                  glm::vec3 (agd::get <0> (translation),
                                             agd::get <1> (translation),
                                             0.0)
                              );
        auto invCenterMat = glm::translate (
                                glm::mat4 (1.0),
                                glm::vec3 (-1 * agd::get <0> (intendedCenter),
                                           -1 * agd::get <1> (intendedCenter),
                                           0.0)
                            );
        auto scaleMat = glm::scale (
                            glm::mat4 (1.0),
                            glm::vec3 (agd::get <0> (scaleFactor),
                                       agd::get <1> (scaleFactor),
                                       1.0)
                        );
        auto centerMat = glm::translate (
                             glm::mat4 (1.0),
                             glm::vec3 (agd::get <0> (intendedCenter),
                                        agd::get <1> (intendedCenter),
                                        0.0)
                         );

        /* Seems that we have to do it this way as opposed to using
         * nested function applications, since that premultiplies? */
        transform = centerMat * scaleMat * invCenterMat * translationMat;             
#if 0
        transform =
            /* Translate back to the intended position, scaled */
            glm::translate (
                /* Scale by the given scale factor */
                glm::scale (
                    /* Translate from the intended position to the origin */
                    glm::translate (
                        /* Translate from the current position to the intended position */
                        glm::translate (
                            glm::mat4 (1.0),
                            glm::vec3 (agd::get <0> (translation),
                                       agd::get <1> (translation),
                                       0.0)
                        ),
                        glm::vec3 (-1 * agd::get <0> (intendedCenter),
                                   -1 * agd::get <1> (intendedCenter),
                                   0.0)
                    ),
                    glm::vec3 (agd::get <0> (scaleFactor),
                               agd::get <1> (scaleFactor),
                               1.0)
                ),
                glm::vec3 ((agd::get <0> (intendedCenter)),
                           (agd::get <1> (intendedCenter)),
                           0.0)
            );
#endif