18、数值计算中的变换、过滤与验证

数值计算中的变换、过滤与验证

1. 变换操作

1.1 核心变换函数 central

以下是 central 函数的代码实现：

cliff_comp *central(a,b,c)
cliff_comp *a,*b,*c; /* result into component c */
{
    double x,y;
    bitmap au,bu;

    au=a->unit;
    bu=b->unit;
    c->unit=(au^bu); /* unit of product */
    switch(u_sign(au,bu)) /* product of units */
    {
        case -1: /* units multiply to -1, negative complex multiply */
            x = (a->coef[1]*b->coef[1])-(a->coef[0]*b->coef[0]);
            y = -((a->coef[0]*b->coef[1])+(a->coef[1]*b->coef[0]));
            break;
        case 0: /* units multiply to zero */
            x = 0.0;
            y = 0.0;
            break;
        case 1: /* units multiply to +1