## 1. Symbolic substitution - MATLAB subs

Subs

This MATLAB function returns a copy of s, replacing all occurrences of old with new, and then evaluates s.

## 2. Evaluate Symbolic Expressions Using subs - MATLAB & Simulink

When you assign a value to a symbolic variable, expressions containing the variable are not automatically evaluated. Instead, evaluate expressions by using subs ...

Evaluate expressions and functions after their variables are assigned values.

## 3. MATLAB: subs, eval - learnOnline

An alternative is to use the eval command. It is of the form ans=eval(S) where S is a symbolic expression for which at least one of its symbolic variables has ...

Variable substitution and expression evaluation: subs, eval Suppose you have a symbolic expression f which includes the symbol x and you wish to substitute for x another symbol c or a numerical value x0. Then you can use the general subs command g=subs(f,old,new) which in our cases would be g=subs(f,x,c) or g=subs(f,x,x0). Here old, new can be arrays. The result g is still a symbolic variable or symbolic constant in “Maple”. Example 1: Consider a function of the two Cartesian coordinates f(x, y) = 2xy/(x2 + y2)2 . Change to polar coordinates using x = r cos θ, y = r sin θ and then determine the value of f at an arbitrary point on the unit circle r = 1. clear all syms x y r theta f=2*x*y/(x^2+y^2)^2; F=subs(f,[x y],[r*cos(theta) r*sin(theta)]); F=simple(F) % previous answer is messy f_on_unit_circle=subs(F,r,1) which gives the output F=sin(2*theta)/r^2 f_on_unit_circle=sin(2*theta) An alternative is to use the eval command. It is of the form ans=eval(S) where S is a symbolic expression for which at least one of its symbolic variables has just been given a value. If all variables are given numerical values, the answer is a number in MATLAB, not “Maple”. Example 2: Let us compare simple MATLAB and “Maple” codes which both evaluate the expression y = (x3 + 2) sec x at x = 0.123. MATLAB code Maple code using subs Maple code using eval clear all clear all clear all x=0.123 syms x syms x y=(x^3+2)*sec(x) S=(x^3+2)*sec(x); S=(x^3+2)*sec(x); y=subs(S,x,0.123) x=0.123; y...

## 4. Substitute Variables in Symbolic Expressions - MATLAB & Simulink

Substitute parameter a with a floating-point number. The toolbox converts numbers to floating-point values, but it keeps intact the symbolic expressions, such ...

Substitute variables with other variables, numbers, vectors, or matrices.

## 5. Substitute Elements in Symbolic Matrices - MATLAB & Simulink

The subs function replaces all b elements in matrix M with the expression a + 1 . Get.

Substitute elements in symbolic matrices.

## 6. Symbolic substitution for multiple variables - MATLAB Answers

Dec 5, 2016 · Say my N is a 6x6 matrix with 5 symbolic variables and I want to evaluate N at one go, for 5 different values of the variables. How do I do that ...

Hi, I wanted some explanation on the captioned. Say my N is a 6x6 matrix with 5 symbolic variables and I want to evaluate N at one go, for 5 different values of the variables. How do I do that u...

## 7. substitution of values in a symbolic function with multiple variables

Nov 30, 2018 · I have a function f(x,y,z) that I have to derive with respect to x, evaluate in a point p(x1,x2,x3) and then elevate that number to the ...

Hi there, I have a function f(x,y,z) that I have to derive with respect to x, evaluate in a point p(x1,x2,x3) and then elevate that number to the power of two, and I'd like to do it all in a matla...

## 8. Matlab recommends me to apply 'subs' command but I have already ...

Jan 22, 2022 · Matlab recommends me to apply 'subs'... Learn more about symbolic, subs command, double command, convert symbolic matrix into numerical ...

Dear all, I am trying to obtain the eigenvalues of a matrix which was previously defined with symbolic variables. Here is a bit of the code: P_simb=[Cf_ss Lo_ss Ro_ss omega_b_ss Tgt_ss K_q_ss ...

## 9. Subs Command for Multivariable Function - MATLAB Answers

Feb 7, 2020 · Direct link to this comment ... Dot between the e and the ^ is needed if x might be non-scalar. Dot between the ) and the *tan is needed if x and ...

syms x y g=(1/2)*e^(-2*x/3).*tan(y+1); subs(g,x,0.3); subs(g,y,-0.7);