: Part of the GNU Compiler Collection (GCC), this is the most popular open-source option. It is a mature compiler that supports Fortran 77 code while also handling newer standards like Fortran 95, 2003, and 2018.

MinGW-w64 from the link in Option 1.

You're looking for a Fortran 77 compiler for Windows 10 64-bit that you can download for free. Here are a few options:

PROGRAM BISECTION DOUBLE PRECISION A, B, C, FA, FB, FC, TOL EXTERNAL F TOL = 1.0D-6 A = 0.0D0 B = 2.0D0 IF (F(A)*F(B) .GE. 0.0) STOP 'No sign change' DO 10 I = 1, 100 C = (A + B) / 2.0D0 FC = F(C) IF (FC .EQ. 0.0 .OR. (B-A)/2.0 .LT. TOL) THEN WRITE(*,*) 'Root: ', C STOP ENDIF FA = F(A) IF (FA*FC .LT. 0.0) THEN B = C ELSE A = C ENDIF 10 CONTINUE END DOUBLE PRECISION FUNCTION F(X) DOUBLE PRECISION X F = X**3 - X**2 - 2.0D0 RETURN END