拟合和绘制抛物线，matlab [英] fitting and plotting a parabola, matlab

问题描述

我有一个非常简单的问题. 我有

I have a very simple problem. I have

x=[ 10 25 50];
y=[ 1.2 3 7.5];

我知道我的曲线拟合功能

I know my curve fitting function

f(x)=(a*x+1)/(bx+c);

如何在matlab中求解系数(a，b，c)并绘制该曲线?

How can I get coefficient(a,b,c) solve in matlab and also plot this curve?

推荐答案

重新排列y = f(x)以使a，b和c为未知数:

Rearrange y = f(x) to make a, b, and c the unknowns:

y = (ax + 1) / (bx + c)
y(bx + c) = ax + 1
ax - bxy - cy = -1;

这描述了当您替换三个成对的x和y值时，a，b和c中的线性方程组的系统.

This describes a system of simultaneous linear equations in a, b, and c when you substitute your three paired values of x and y.

x      = [10, 20, 100];
y      = [1.2, 0.7, 0.4];
coeffs = [x', (-x.*y)', -y'];
knowns = [-1, -1, -1]';

v      = coeffs \ knowns;        % v is [a; b; c]

现在您有了系数a，b和c，因此可以绘制函数.

Now you have the coefficients a, b, and c so you can plot the function.

要绘制函数，请首先选择数据点的x值

To plot a function, first choose the x-values of the data points

xt = 1:100;

然后计算y值(假设您已经有a，b，c)

Then calculate the y-values (assuming you've already got a, b, c)

yt = (a*x + 1) ./ (b*x + c)

然后只是将它们绘制出来！

Then just plot them!

plot(xt, yt);

阅读有关绘图功能的Matlab帮助，以自定义绘图样式.

Read the Matlab help on the plot function for customizing the style of the plot.

这篇关于拟合和绘制抛物线，matlab的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！