[MATLAB基础] 请教matlab定点计算溢出的问题

[az1981cn]

T.F = fimath('SumMode','SpecifyPrecision', 'SumWordLength', 10, 'SumFractionLength', 4);
a=fi(-32,1,10,4,T.F)
b=fi(-1.5,1,10,4,T.F)
c=fi(-25.9375,1,10,4,T.F)
d=fi(9,1,10,4,T.F)

K>> a+b+c+d

ans = 

   -23

          DataTypeMode: Fixed-point: binary point scaling
            Signedness: Signed
            WordLength: 10
        FractionLength: 4

        RoundingMethod: Nearest
        OverflowAction: Saturate
           ProductMode: FullPrecision
               SumMode: SpecifyPrecision
         SumWordLength: 10
     SumFractionLength: 4
         CastBeforeSum: true

为什么输出结果是-23，而不是-32呢？