Error using symengine, Too many input arguments

i hvae this code

f=@(MV,red_P) red_P - 8*redT/(8*MV-1) +27/(64*MV^2); 
dp_dMV=diff(sym (f)); 
dp_dMV=matlabFunction(dp_dMV); 
 

when I run it , it shows me this

Error using symengine>@()1.0
Too many input arguments.

but my friend have the same code with different names and it is working

this is her

f=@(phi,P_r) P_r - 8*Tr/(8*phi-1) +27/(64*phi^2); 
dp_dphi=diff(sym(f));
dp_dphi=matlabFunction(dp_dphi); 

[madhan ravi]

provide the datas needed to run your code

[Wafaa Alnakhli]

how ?

[madhan ravi]

does the variables have any values?

[Wafaa Alnakhli]

ooh sorry

this is it

MV=0.15:0.02:1.75; %create Molar Volume array 
redT=0.85:0.05:1; %create Temperature  array

Answer 1

[madhan ravi]

syms Tr P_r P_r phi
f=@(phi,P_r) P_r - 8*Tr/(8*phi-1) +27/(64*phi^2); 
dp_dphi=diff(sym(f));
dp_dphi=matlabFunction(dp_dphi);

[Wafaa Alnakhli]

it shows me this error

The following error occurred converting from sym to double:
Unable to convert expression into double array.

[madhan ravi]

try clear all at the very begining if your code

[Wafaa Alnakhli]

yes I have