Problems with matrix dimensions not agreeing

2 次查看（过去 30 天）
Yianni
Yianni 2015-2-4
回答： Guillaume 2015-2-4
I am having issues with my matrix dimensions and getting this error in my code:
Error using /
Matrix dimensions must agree.
I used dot arithmatic but that does not seem to be the issue. It seems very simple to fix but I cannot figure out what the problem is. The issue is specifically for the variables "lnY1" and "lnY2". My code is below:
x1 = [0.0374 0.0972 0.3141 0.5199 0.7087 0.9193 0.9591];
%Data from Experimental Results
lny1 = [2.0937 1.6153 0.7090 0.3136 0.1079 0.0002 -0.0077];
lny2 = [0.0220 0.0519 0.2599 0.5392 0.8645 1.3177 1.3999];
%Data from Calculations
x2 = 1-x1;
L12 = 0.124; L21 = 0.523;
lnY1 = -log(x1+(L12*x2))+x2*((L12/(x1+(L12*x2)))-(L21/(x2+(L21*x1))));
lnY2 = -log(x2+(L21*x1))-x1*((L12/(x1+(L12*x2)))-(L21/(x2+(L21*x1))));
plot(x1,lny1,x1,lny2,x1,lnY1,x1,lnY2),grid on
title('Activity Coefficients for Ethanol/Benzene')
xlabel('x_1'),ylabel('y')

请先登录，再回答此问题。

回答（1 个）

Guillaume
Guillaume 2015-2-4
The best way for you to work out the problem would be to try each subexpression on its own and move toward more complex ones if it works.
Anyway, element-wise multiplication is .*, division of scalar by a matrix or element-wise division is ./:
lnY1 = -log(x1+(L12*x2))+x2.*((L12./(x1+(L12*x2)))-(L21./(x2+(L21*x1))));
lnY2 = -log(x2+(L21*x1))-x1.*((L12./(x1+(L12*x2)))-(L21./(x2+(L21*x1))));
If in doubt, and you do mean to operate element-wise, replace each operator +, -, *, /, ^ by its dotted equivalent.

类别

在 Help Center 和 File Exchange 中查找有关 Resizing and Reshaping Matrices 的更多信息

标签

Community Treasure Hunt

Find the treasures in MATLAB Central and discover how the community can help you!

Start Hunting!

Translated by