I am applying to a number of Physics REUs that require 2 letters of recommendation. I am having my Physics Lab professor write one, but am considering having my linear algebra professor write another. Her class was smaller than all others (besides lab), so I think she can provide the best representation of my academic skills and personality. She was also the only professor who graded work other than my exams, so she would be better able to speak of the quality of work I produce and my growth over the semester. Will it hurt my chances that she is not a physics professor? I am only a sophomore, so I don't have many other professors who I feel could write a strong, personal recommendation.