How can I put the results from a while loop in a matrix?

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Kaicheng Pan 2020-5-14

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此问题的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/525340-how-can-i-put-the-results-from-a-while-loop-in-a-matrix

评论： Kaicheng Pan 2020-5-14

So basically I am solving an equation using trial and error. Here's the code

clear;clc;
syms x y
a1=13.7819; b1=2726.81; c1=217.512;
a2=13.9726; b2=3259.93; c2=212.3;
for x=0:10
    t=70;
    psat1=exp(a1-b1/(t+c1));
    psat2=exp(a2-b2/(t+c2));
    p=0.1*x*psat1+(1-0.1*x)*psat2;
    while abs(p-90)>5
        t=t+1;
        psat1=exp(a1-b1/(t+c1));
        psat2=exp(a2-b2/(t+c2));
        p=0.1*x*psat1+(1-0.1*x)*psat2;
    end
    t(x+1)=t
end

I want to put the t from each for loop into one matrix, but Matlab spits out this:

t=131
t=119 119
t=111 0 111
t=103 0 0 103 and so on

I don't know why! Please help

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Answer 1

Geoff Hayes 2020-5-14

1
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此回答的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/525340-how-can-i-put-the-results-from-a-while-loop-in-a-matrix#answer_432363

在 MATLAB Online 中打开

Kaicheng - you probably can remove the line

syms x y

since I can't see the y being used in the code, and the x is overridden by the loop step variable. A problem is that you are treating t as if it were an array (at one line of code) and then as a scalar (at another line of code)

for x=0:10
    t=70;                               % <---- here t is a scalar and is being reset on each iteration
    psat1=exp(a1-b1/(t+c1));
    psat2=exp(a2-b2/(t+c2));
    p=0.1*x*psat1+(1-0.1*x)*psat2;
    while abs(p-90)>5
        t=t+1;
        psat1=exp(a1-b1/(t+c1));
        psat2=exp(a2-b2/(t+c2));
        p=0.1*x*psat1+(1-0.1*x)*psat2;
    end
    t(x+1)=t                            % <---- here t is an array
end

Try creating an array for your t values:

tArray = zeros(11,1);
for x=0:10
    t=70;
    psat1=exp(a1-b1/(t+c1));
    psat2=exp(a2-b2/(t+c2));
    p=0.1*x*psat1+(1-0.1*x)*psat2;
    while abs(p-90)>5
        t=t+1;
        psat1=exp(a1-b1/(t+c1));
        psat2=exp(a2-b2/(t+c2));
        p=0.1*x*psat1+(1-0.1*x)*psat2;
    end
    tArray(x+1)=t;
end