How to feel confident with knowledge if I have not taken relevant classes during my postgraduate degree? Taking relevant courses builds up confidence, exposure and depth. I managed to get my master's degree and PhD degree in computational chemistry without taking any graduate level mathematics and modeling courses.
On top of this, the only maths I had was till my 3rd year undergrad and I struggled with it. I scored a C grade in every exams and I was/and still am not comfortable with it.
I am decent with linear algebra and multivariable calculus and work with tensor analysis in my research. Each of these I had taken only in my undergrad.
I should have taken relevant courses during my master's and PhD. Though I can perform well in my research (currently a postdoc), I feel unconfident and uncomfortable with my level of knowledge as I have never explored the depth of the subjects as is done in graduate courses. I only self-studied what was needed in my research.
How to feel confident with knowledge if I have not taken relevant classes during my postgraduate degree?
The classes from undergrad and what you took from them enabled you to self-study all the relevant maths on your own. That is a much more valuable thing than the knowledge on its own and should give you the confidence.
If you absolutely need the &quot;external validation&quot; to build the confidence: As a postdoc you are still in a University setting? Then why not take some time out of your schedule and take the classes now? Or take some online courses that include tests and a certificate.