Arithmetic Operations for mytype Numbers

Below x, y, z are of type mytype.

void dd_add(x, y, z)

:
Set x to be the sum of y and z.

void dd_sub(x, y, z)

:
Set x to be the substraction of z from y.

void dd_mul(x, y, z)

:
Set x to be the multiplication of y and z.

void dd_div(x, y, z)

:
Set x to be the division of y over z.

void dd_inv(x, y)

:
Set x to be the reciplocal of y.