# Unable to plot inequality region

4 次查看（过去 30 天）
YLieven 2022-6-18

This is the solution I am trying to mimic, but for my case it does not seem to work:
syms ki kd
cond = [ -9*ki, 10*ki - 10*kd + 10, 360*kd - 24*ki + 1320]; % My 3 inequality conditions
Unrecognized function or variable 'ki'.
r = -5:0.01:5;
[ki, kd] = meshgrid(r);
condition1 = cond(1) > 0;
condition2 = cond(2) > 0;
condition3 = cond(3) > 0;
output = ones(length(r));
output(~(condition1 & condition2 & condition3)) = 0; % this fails
imshow(output, 'xdata', r, 'ydata', r);
axis on;
the line that fails gives me this error:
Error using symengine
Unable to prove '~0 < -9*ki | ~0 < 10*ki - 10*kd + 10 |
~0 < 360*kd - 24*ki + 1320' literally. Use 'isAlways' to
test the statement mathematically.
Error in sym/subsindex (line 841)
X =
1;
How can I solve this? It seems like it should be such a simple thing to do, but I can't make it work.

### 采纳的回答

KSSV 2022-6-18

r = -5:0.01:5;
[ki, kd] = meshgrid(r);
cond = -9*ki>0 & 10*ki - 10*kd + 10>0 & 360*kd - 24*ki + 1320>0; % My 3 inequality conditions
% output = ones(length(r));
% output(~(condition1 & condition2 & condition3)) = 0; % this fails
imshow(cond, 'xdata', r, 'ydata', r);
axis on;
##### 3 个评论显示 1更早的评论隐藏 1更早的评论
KSSV 2022-6-18
Replace zeros with Nan and use surf.
YLieven 2022-6-18
It works! Thank you.

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