8字怎么教孩子写
替您的孩子感到幸福,真是为有心的家人,我个人认为如果孩子很小,8不太会拐弯的话,最好的方法就是先让他画圆,圆画的很漂亮了,然后将两个圆粘在一起不就是8了吗,等稍大些了,在纠正,给予正确的书写方法,小孩子不管写什么东西都是从涂鸦开始的,一定要有耐心,多给予鼓励哦,加油!
版权声明:本文为博主原创文章,遵循 CC 4.0 BY-SA版权协议,转载请附上原文出处链接和本声明。<br>曲线面积的求法:<br>(1)任意曲线的面积求法:<br>>> x=0:pi/100:pi; >> y=sin(x); >> trapz(x,y) ans = 1.9998<br>(2)ROC曲线的面积求法:function auc=auc(FPR,TPR) % given true positive rate and false positive rate calculates the area under the curve % true positive are on the y-axis and false positives on the x-axis % sum rectangular area between all points % example: auc=auc(FPR,TPR); [x2,inds]=sort(FPR); x2=[x2,1]; % the trick is in inventing a last point 1,1 y2=TPR(inds); y2=[y2,1]; xdiff=diff(x2); %xdiff xdiff=[x2(1),xdiff]; auc1=sum(y2.*xdiff); % upper point area auc2=sum([0,y2([1:end-1])].*xdiff); % lower point area auc=mean([auc1,auc2]); end