not able to evaluate the value for an equation using the data from a table, table is three columns data
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kaixi gu
am 10 Sep. 2022
Bearbeitet: Seth Furman
am 13 Sep. 2022
%creat symbol for axial force, length, thickness, displacemnent and width
syms f l t d w
%define governing equations for parameter
stress = f./(t*w)
strain = d./l
%measurement resolution and uncertainty
%zeroth order uncertainty
%define symbolic data
T = readtable('Intro_specimen 2.txt');
f = T(:,2);
l = 6.125;
t = 0.057;
d = T(:,1);
w = 0.414;
%substitute value into equation
stress = eval(stress);
strain = eval(strain);
3 Kommentare
Walter Roberson
am 10 Sep. 2022
stress = eval(stress);
Never eval() a symbolic object. eval() of a symbolic object is not formally defined, but in practice it is equivalent to eval(char(TheSymbolicObject)) . That is a problem because the character representation of symbolic objects is in a computer language that is not MATLAB and is not the internal MuPAD programming language.
syms x real
y = piecewise(3 < x & x < 5, 2, 4)
char(y)
x = pi
eval(y)
... which is happening because "x in Dom::Interval" is not valid MATLAB syntax.
Pulkit
am 13 Sep. 2022
Try using 'readmatrix' function instead of 'readtable' as readtable outputs table object which is not supported by element wise operations. If problem still presist please share the exact error message you are getting and also type of data in Intro_specimen 2.txt
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Seth Furman
am 13 Sep. 2022
Bearbeitet: Seth Furman
am 13 Sep. 2022
You just need to change the parentheses-() to curly braces-{} when pulling data of the table.
T = array2table(magic(3))
%creat symbol for axial force, length, thickness, displacemnent and width
syms f l t d w
%define governing equations for parameter
stress = f./(t*w)
strain = d./l
%measurement resolution and uncertainty
%zeroth order uncertainty
%define symbolic data
f = T{:,2}; % <-- curly braces instead of parentheses
l = 6.125;
t = 0.057;
d = T{:,1}; % <-- curly braces instead of parentheses
w = 0.414;
%substitute value into equation
stress = eval(stress)
strain = eval(strain)
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