从列表中挑选具有共同属性的元素
现有一多项式的根组成的列表,如何挑出位于复平面第一象限的根?查了下select命令,没搞明白类型的应用 应该是这样吧.
restart;
f:=add(x^i,i in [$0..10]);
sol:=:
Vector(sol);
f:=1+x+x^2+x^3+x^4+x^5+x^6+x^7+x^8+x^9+x^10
-0.95949297361-0.28173255684*I
-0.95949297361+0.28173255684*I
-0.65486073395-0.75574957435*I
-0.65486073395+0.75574957435*I
-0.14231483827-0.98982144188*I
-0.14231483827+0.98982144188*I
+0.41541501300-0.90963199535*I
+0.41541501300+0.90963199535*I
+0.84125353283-0.54064081746*I
+0.84125353283+0.54064081746*I
<select(x->Re(x)>=0 and Im(x)>=0,sol)>;
+0.41541501300+0.90963199535*I
+0.84125353283+0.54064081746*I 多谢斑竹,
我试了另外一个,好像也可以
remove(has,[],indets([],negative)) 这样更简单:remove(hastype,sol,negative); 明白了,多谢
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