How to get actual value instead of answer in terms of exp and pi as a output in matlab program

mf=0.5217;

Cp1=2253.22;

Ar=1.7593;

U_L=3.1314;

F_=0.8726;

F_1 = ((mf*Cp1)/(Ar*U_L))*(1-(exp(-((U_L*F_*Ar)/(mf*Cp1)))))

When I am calculating F_1 using above lines it gives a specified value like 0.9223 but when I am using the same formula for F_1 at the end of for loop and values of mf, Cp1 are calculated in loop and Ar, U_L,F_ , are calculated at the end f the loop then F_1 gives value like

-(670.3687109128533118179408369425*(exp(-0.0013017227863710711508658689494424*pi) - 1))/pi.

What could be the reason for this and how to get rid of it...??

Answer 1

[Steven Lord]

If you want to perform the calculations symbolically but then receive a double precision or numeric result, call double (if your expression does not contain any symbolic variables) or vpa (if it does) on the final result.

[ANUBHAV GOEL]

Thanks, calling double has done the trick.

[JUAN MANUEL PALAO]

Hi! Same question here but when using vpasolve function with a symbolic variable:

syms X

sigma=vpasolve(-DF+1-sin(beta1)/(mi*sin(beta2))+(ni*sin(beta1)^2)/(X*(ni+1))*((1-ni^2)/(mi*ni*psi)- cot(beta1)+cot(beta2)/(mi*ni))*(1-(M1^2*sin(beta1))/(mi*sin(beta2))*(sin(beta1)/(mi*sin(beta2)-1))),X,1);

The thing is that it does give a numerical result of "sigma", however, the variables I calculate after and depend on "sigma" are expressed in terms of pi, /, +, ^, etc.

How should I make that call "vpa" you mentioned?

Thank you in advance.

[Steven Lord]

two = sym(2);
s = sqrt(two)

s = 

vpa(s, 6)

ans = 

1.41421

double(s) % Since s contains no symbolic variable this works

ans = 1.4142

Answer 2

[the cyclist]

I think there must be some other difference, not just being in a loop. It looks like somehow you have the Symbolic Math Toolbox involved in there. Do you see a syms command before the loop? Can you post the code that gives the two different results?

[ANUBHAV GOEL]

Thanks for reply. Yes, you are right syms are involved in the code. how can this be corrected then. all other outputs are coming with specific values except F_1.

[ANUBHAV GOEL]

Syms commands are used within the loop.

[the cyclist]

If you want to do all numeric calculations, and none symbolic, then presumably you can just remove all the syms commands.