如何繪製帶定製座標軸的圖形

Question

我對此表示歉意，我相信這是一個簡單的任務，但我不知道該怎麼做。

假設我有一個公式y = (exp(-x) + x^2)/sqrt(pi(x)，我想將它繪製爲y與x^2。

這是怎麼回事？

Answer 1

像這樣：

X = 0:0.1:5; %// Get the x values 
x = X.^2;  %// Square them 
%// Your formula had errors, I fixed them but I could have misinterpreted here, please check 
y = (exp(-x) + x.^2)./sqrt(pi*x); %// Calculate y at intervals based on the squared x. This is still y = f(x), I'm just calculating it at the points at which I want to plot it. 

plot(x,y) %//Plot against the square X. 

在這一點上，這是一種具有隻是沒有不同繪製它正常。你想要的是使刻度標記的值爲X.^2。這不會改變y值，也不會扭曲功能，它只是改變了視覺效果。類似密謀反對數比例：

set(gca, 'XTick', X.^2) %//Set the tickmarks to be squared 

第二個方法讓你像一個陰謀

編輯：

其實我覺得你問的這個：

x = 0:0.1:5; 
y = x.^2; %// Put your function in here, I'm using a simple quadratic for illustrative purposes. 
plot(x.^2,y) %//Plot against the square X. Now your y values a f(x^2) which is wrong, but we'll fix that later 
set(gca, 'XTick', (0:0.5:5).^2) %//Set the tickmarks to be a nonlinear intervals 
set(gca, 'XTickLabel', 0:0.5:5) %//Cahnge the labels to be the original x values, now accroding to the plot y = f(x) again but has the shape of f(x^2) 

所以我在這裏繪製一個簡單的二次曲線，但如果我將它繪製成平方它應該變成線性的。但是我仍然想讀出y = x^2而不是y = x的圖，我只是想讓它看起來像y = x。因此，如果我讀取該圖上x值爲4的y值，我將得到16，這仍然是相同的正確的原始y值。

Answer 2

這裏是我的答案是：它類似於丹的一個，但根本的不同。你可以計算的y值作爲x功能，但繪製它們作爲x^2的功能，這是什麼OP是問，如果我的理解是正確的：

x = 0:0.1:5; %// Get the x values 
x_squared = x.^2;  %// Square them 
%// Your formula had errors, I fixed them but I could have misinterpreted here, please check 
y = (exp(-x) + x.^2)./sqrt(pi*x); %// Calculate y based on x, not the square of x 

plot(x_squared,y) %//Plot against the square of x 

正如丹所提到的，您可以隨時改變刻度線：

x_ticks = (0:0.5:5).^2; % coarser vector to avoid excessive number of ticks 
set(gca, 'XTick', x_ticks) %//Set the tickmarks to be squared