Senteces: Define, determine or calculate?

1. As X is defined(I've used "define" not "determine" as there is a well-known formula) as formula then the determination(because I'll calculate the concrete value) of unknown parameter Y comes in fact(I mean that the general problem become simpler in the particular case) to the ...

2. ... where elements of the series are related by equation, determined by the Kirchhoff law

3. The rest of coefficients is(are?) calculated(or determined?) with the recurrent relation.

4. As result of the convolution of fraction, with a glance of the adjustment coefficient defined before, the function in fractionally rational form is determined as: formula

5. The transform is carried out within the general frequency band, limited by the critical frequency determined(calculated? defined?) before