Undefined function 'symsum' for input arguments of type 'double'. for terahert band system model

I am trying to code a system model in the terahertz band

This is my code and I have this error

Undefined function 'symsum' for input arguments of type 'double'.

close all; clear all;

clc

freq = 275*10^9;

eta = 4;

c= 3*10^8;

gt=10^5.5;

gr=gt;

d=30;

lambda = c/freq;

k=THz_Pathloss(freq);

path_gain_thz= ((c*sqrt(gt*gr))./(4*pi*freq*d)).*exp(-0.5*k*d); % hL = hAL * hFL

signal_bw = 10*10^9;

noise_psd = 3.8*10^(-17);

noise_power = noise_psd*signal_bw;

signal_power_dbm= -20:10:60;

signal_power_lin = 10.^(signal_power_dbm/10)*10^(-3);

power_noise_ratio_db = 20:10:60; %signal_power_dbm-noise_power_dbm;

power_noise_ratio = 10.^(power_noise_ratio_db/10);

cc=symsum(signal_bw,6)*log2*{1+ (2/noise_psd*k)};

Undefined function 'symsum' for input arguments of type 'double'.

Error in Energy_Model_WSNN (line 19)

cc=symsum(signal_bw,6)*log2*{1+ (2/noise_psd*k)};

Answer 1

[Sharmin Kibria]

Hi,

If you are calling symsum with two inputs, the first input has to be a symbolic expression. As you are entering signal_bw as a numeric, the function is erroring out. Please refer to the documentation below for proper format of input arguments.

https://www.mathworks.com/help/symbolic/symsum.html?searchHighlight=symsum&s_tid=srchtitle

Thanks

Sharmin