I want to change the symbolic variables in my matrix to numbers

Question

Charles 2024-4-17

0
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此问题的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/2108071-i-want-to-change-the-symbolic-variables-in-my-matrix-to-numbers

评论： Star Strider 2024-4-17

To make it simpler to explain, I just want to plot the results of this final matrix. But it gives me zero as the answer because it is in a symbolic format. Is there a way to change it to the actual value ?

clear all ; close all; close ; clear

syms s

Expr = (sin(s));

F1 = int(Expr)

F1 =

syms n

expr2 = 1/n ;

F2 = int(expr2)

F2 =

total = F2 == F1

total =

final = isolate(total,n)

final =

want2plot = subs(final,s,0:0.1:5)

want2plot =

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Answer 1

Star Strider 2024-4-17

0
链接

此回答的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/2108071-i-want-to-change-the-symbolic-variables-in-my-matrix-to-numbers#answer_1443061

编辑：Star Strider 2024-4-17

在 MATLAB Online 中打开

Use the fplot function —

clear all ; close all; close ; clear

syms s

Expr = (sin(s));

F1 = int(Expr)

F1 =

syms n

expr2 = 1/n ;

F2 = int(expr2)

F2 =

total = F2 == F1

total =

final = isolate(total,n)

final =

want2plot = subs(final,s,0:0.1:5)

want2plot =

figure

fplot(rhs(final), [0 5])

grid

xlabel('s')

ylabel('n')

title('‘fplot’')

Alternatively —

nfcn = matlabFunction(rhs(final))

nfcn = function_handle with value:

@(s)exp(-cos(s))

figure

plot((0:0.1:5), nfcn(0:0.1:5))

grid

xlabel('s')

ylabel('n')

title('‘matlabFunction’')

figure

plot(0:0.1:5, double(rhs(want2plot)))

grid

xlabel('s')

ylabel('n')

title('‘want2plot’')

EDIT — Added the ‘Alternatively —’ section.

EDIT — (16 Apr 2024 at 12:33)

Added independent variable to ‘want2plot’ and added titles.

.

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Charles 2024-4-17

Thank you very much!! That makes sense, i saw somewhere that you could use the rhs and lhs for stuff but didn't think of using it like this to get the answer.