In the final example, the value of the HOME variable is tested to see if it is a directory using the -d unary operator.
在最后一个示例中,测试home变量的值,用单目操作符- d检查它是不是目录。
2
In order to reconstruct the shape of scatterer d, we establish the relation between the scatterer and the far field pattern. The relation can be fixed by so called far field operator f.