[Bug-apl] Complex minus float gives wrong result

[Kevin Anderson]

Subtract with a complex on the left and a float on the right acts as if the operands were swapped:

 

    2J8 - 3.0

1J¯8

    3.0 - 2J8

1J¯8

 

However, complex minus int or int minus complex is OK:

    2J8 - 3

¯1J8

    3 - 2J8

1J¯8

 

FloatCell.cc::bif_subtract is executing "return A->bif_subtract(Z, this)" when A is not a real, no doubt inspired by the pattern used in FloatCell::bif_add. It should rather take its inspiration from IntCell::subtract and do "bif_negative(Z); return A->bif_add(Z,Z);" instead.