github.com/jingcheng-WU/gonum@v0.9.1-0.20210323123734-f1a2a11a8f7b/mathext/internal/amos/amoslib/zmlt.f (about)

     1        SUBROUTINE ZMLT(AR, AI, BR, BI, CR, CI)
     2  C***BEGIN PROLOGUE  ZMLT
     3  C***REFER TO  ZBESH,ZBESI,ZBESJ,ZBESK,ZBESY,ZAIRY,ZBIRY
     4  C
     5  C     DOUBLE PRECISION COMPLEX MULTIPLY, C=A*B.
     6  C
     7  C***ROUTINES CALLED  (NONE)
     8  C***END PROLOGUE  ZMLT
     9        DOUBLE PRECISION AR, AI, BR, BI, CR, CI, CA, CB
    10        CA = AR*BR - AI*BI
    11        CB = AR*BI + AI*BR
    12        CR = CA
    13        CI = CB
    14        RETURN
    15        END