# why use limit function goes wrong

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warnerchang2022-4-9
syms x
f=(2/pi*atan(x))^x;
limit(f,x,inf,'right')
Prompt：Inconsistent limit direction.
however，I tried to transform the f and used limit function to get the limit. It has a result.
% y = 1 - 2 / pi * atan( x ); % transformation，x -> ∞ ，y -> 0
% x = tan( pi/2 - pi/2 * y ); % equation
syms y
f = ( 1 - y ) .^ ( tan( pi/2 - pi/2 * y ) )
limit( f, y, 0 )
ans =
exp(-2/pi)

### 采纳的回答

Walter Roberson 2022-4-9
Asking for the "right" limit means that you want the limit from above. As you are asking for the limit at infinity, that would be asking for the limit from "above" infinity. However, MATLAB does not have any support for transfinite numbers.
##### 2 个评论显示隐藏 1更早的评论
Walter Roberson 2022-4-9
syms x
f=(2/sym(pi)*atan(x))^x;
limit(f,x,inf,'left')
MATLAB does not identify 2/pi (numeric double precision) as being the same as 1/(π/2) (the symbolic limit)

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