Converting result after substituting numerical values into symbolic expression not possible. Matlab creates new symbolic variables by complex symbolic expression.
I have 22 symbolic variables, which I create different subexpressions with. Then I mathematically combine all these subexpression in one big expression according to the calculation I have to perform. I do these steps to keep some readability. However, matlab automatically creates new variables in the final expression, whereby they are named sigmas. When I then substitute numerical values into the symbolic variables, I get a complex result, which I can convert into a double precision number. However, I need to compute the derivative first and then substitute numerical values and at that point I get the error that it is not possible to convert them because symbolic variabls remains in the expression. I suppose that’s because of the new sigma variables. I tried vpa(), double(), simplify() but I do not get it solved. Does someone have an idea how I could handle that ? You can see that the derivative result is displayed with a D if you open the result and not sigma can be seen like it is displayed in the script.
syms T_NTC NTC_R NTC_B2585 R1509 R1510 R1507 S3V3S_A Ron LeakageCurrent GainError OffsetError VOLT_REF_3V INLError DNLError S3V3S_A_Ripple PSRR ResolutionADC
syms R1508 R1511 ADC2ADC_GainError ADC2ADC_OffsetError ADC2ADC_Isolation
%% Resistor network TEMP_DCB
R_NTC = NTC_R.*exp(NTC_B2585*(1./(T_NTC)-1/298.15));
Rs_TEMP_DCB = R1509 + 1./(1./R1510+1./R_NTC+1./R1507);
TEMP_DCB = S3V3S_A.*(R_NTC.*R1510./(R_NTC+R1510))./(R_NTC.*R1510./(R_NTC+R1510)+R1507) + (Rs_TEMP_DCB+Ron).*LeakageCurrent;
ADC_error_TEMP_DCB = GainError.*TEMP_DCB./VOLT_REF_3V + OffsetError + INLError + DNLError + S3V3S_A_Ripple*10.^(-PSRR/20).*2.^ResolutionADC./VOLT_REF_3V;
TEMP_DCB_ADCRawValue = round(TEMP_DCB.*2^ResolutionADC./VOLT_REF_3V + ADC_error_TEMP_DCB);
%% Resistor network 3V3S_A
Rs_VOLT_3V3S_A = R1508.*R1511./(R1508+R1511);
VOLT_3V3S_A = S3V3S_A.*R1511./(R1511+R1508) + (Rs_VOLT_3V3S_A+Ron).*LeakageCurrent;
ADC_error_3V3S_A = (GainError+ADC2ADC_GainError).*VOLT_3V3S_A./VOLT_REF_3V + OffsetError + ADC2ADC_OffsetError + ADC2ADC_Isolation + INLError + DNLError + S3V3S_A_Ripple*10.^(-PSRR/20).*2.^ResolutionADC./VOLT_REF_3V;
VOLT_3V3S_A_ADCRawValue = round(VOLT_3V3S_A.*2^ResolutionADC./VOLT_REF_3V + ADC_error_3V3S_A);
%% Ratio TEMP_DCB/VOLT_3V3S_A
y = TEMP_DCB_ADCRawValue./VOLT_3V3S_A_ADCRawValue
%% Derivatives
dy_dNTC_R = diff(y, NTC_R);
dy_dNTC_B2585 = diff(y, NTC_B2585);
dy_dR1509 = diff(y, R1509);
dy_dR1510 = diff(y, R1510);
dy_dR1507 = diff(y, R1507);
dy_dS3V3S_A = diff(y, S3V3S_A);
dy_dRon = diff(y, Ron);
dy_dLeakageCurrent = diff(y, LeakageCurrent);
dy_dGainError = diff(y, GainError);
dy_dVOLT_REF_3V = diff(y, VOLT_REF_3V);
dy_dOffsetError = diff(y, OffsetError);
dy_dINLError = diff(y, INLError);
dy_dDNLError = diff(y, DNLError);
dy_dS3V3S_A_Ripple = diff(y, S3V3S_A_Ripple);
dy_dPSRR = diff(y, PSRR);
dy_dResolutionADC = diff(y, ResolutionADC);
dy_dR1508 = diff(y, R1508);
dy_dR1511 = diff(y, R1511);
dy_dADC2ADC_GainError = diff(y, ADC2ADC_GainError);
dy_dADC2ADC_OffsetError = diff(y, ADC2ADC_OffsetError);
dy_dADC2ADC_Isolation = diff(y, ADC2ADC_Isolation);
%% Define working points
% Define your working point values
T_NTC_wp1 = 130 + 273.15;
NTC_R_wp1 = 5e3;
NTC_B2585_wp1 = 3420;
R1509_wp1 = 1e3;
R1510_wp1 = 20e3;
R1507_wp1 = 2e3;
S3V3S_A_wp1 = 3.33;
Ron_wp1 = 500;
LeakageCurrent_wp1 = 0;
GainError_wp1 = 0;
OffsetError_wp1 = 0;
VOLT_REF_3V_wp1 = 3;
INLError_wp1 = 0;
DNLError_wp1 = 0;
S3V3S_A_Ripple_wp1 = 10e-3;
PSRR_wp1 = 57;
ResolutionADC_wp1 = 12;
R1508_wp1 = 1e3;
R1511_wp1 = 1e3;
ADC2ADC_GainError_wp1 = 0;
ADC2ADC_OffsetError_wp1 = 0;
ADC2ADC_Isolation_wp1 = 0;
%% Combine working points into a vector
WP1 = [T_NTC_wp1 NTC_R_wp1 NTC_B2585_wp1 R1509_wp1 R1510_wp1 R1507_wp1 S3V3S_A_wp1 Ron_wp1 …
LeakageCurrent_wp1 GainError_wp1 OffsetError_wp1 VOLT_REF_3V_wp1 INLError_wp1 …
DNLError_wp1 S3V3S_A_Ripple_wp1 PSRR_wp1 ResolutionADC_wp1 R1508_wp1 R1511_wp1 …
ADC2ADC_GainError_wp1 ADC2ADC_OffsetError_wp1 ADC2ADC_Isolation_wp1];
%% Calculate sensitivity
symbols = [T_NTC NTC_R NTC_B2585 R1509 R1510 R1507 S3V3S_A Ron LeakageCurrent GainError OffsetError …
VOLT_REF_3V INLError DNLError S3V3S_A_Ripple PSRR ResolutionADC R1508 R1511 ADC2ADC_GainError …
ADC2ADC_OffsetError ADC2ADC_Isolation];
S_NTC_R_wp1 = (subs(dy_dNTC_R, symbols, WP1) * NTC_R_wp1) / subs(y, symbols, WP1)
% S_NTC_R_wp1_num = double(S_NTC_R_wp1);
S_NTC_R_wp1_num = vpa(S_NTC_R_wp1);I have 22 symbolic variables, which I create different subexpressions with. Then I mathematically combine all these subexpression in one big expression according to the calculation I have to perform. I do these steps to keep some readability. However, matlab automatically creates new variables in the final expression, whereby they are named sigmas. When I then substitute numerical values into the symbolic variables, I get a complex result, which I can convert into a double precision number. However, I need to compute the derivative first and then substitute numerical values and at that point I get the error that it is not possible to convert them because symbolic variabls remains in the expression. I suppose that’s because of the new sigma variables. I tried vpa(), double(), simplify() but I do not get it solved. Does someone have an idea how I could handle that ? You can see that the derivative result is displayed with a D if you open the result and not sigma can be seen like it is displayed in the script.
syms T_NTC NTC_R NTC_B2585 R1509 R1510 R1507 S3V3S_A Ron LeakageCurrent GainError OffsetError VOLT_REF_3V INLError DNLError S3V3S_A_Ripple PSRR ResolutionADC
syms R1508 R1511 ADC2ADC_GainError ADC2ADC_OffsetError ADC2ADC_Isolation
%% Resistor network TEMP_DCB
R_NTC = NTC_R.*exp(NTC_B2585*(1./(T_NTC)-1/298.15));
Rs_TEMP_DCB = R1509 + 1./(1./R1510+1./R_NTC+1./R1507);
TEMP_DCB = S3V3S_A.*(R_NTC.*R1510./(R_NTC+R1510))./(R_NTC.*R1510./(R_NTC+R1510)+R1507) + (Rs_TEMP_DCB+Ron).*LeakageCurrent;
ADC_error_TEMP_DCB = GainError.*TEMP_DCB./VOLT_REF_3V + OffsetError + INLError + DNLError + S3V3S_A_Ripple*10.^(-PSRR/20).*2.^ResolutionADC./VOLT_REF_3V;
TEMP_DCB_ADCRawValue = round(TEMP_DCB.*2^ResolutionADC./VOLT_REF_3V + ADC_error_TEMP_DCB);
%% Resistor network 3V3S_A
Rs_VOLT_3V3S_A = R1508.*R1511./(R1508+R1511);
VOLT_3V3S_A = S3V3S_A.*R1511./(R1511+R1508) + (Rs_VOLT_3V3S_A+Ron).*LeakageCurrent;
ADC_error_3V3S_A = (GainError+ADC2ADC_GainError).*VOLT_3V3S_A./VOLT_REF_3V + OffsetError + ADC2ADC_OffsetError + ADC2ADC_Isolation + INLError + DNLError + S3V3S_A_Ripple*10.^(-PSRR/20).*2.^ResolutionADC./VOLT_REF_3V;
VOLT_3V3S_A_ADCRawValue = round(VOLT_3V3S_A.*2^ResolutionADC./VOLT_REF_3V + ADC_error_3V3S_A);
%% Ratio TEMP_DCB/VOLT_3V3S_A
y = TEMP_DCB_ADCRawValue./VOLT_3V3S_A_ADCRawValue
%% Derivatives
dy_dNTC_R = diff(y, NTC_R);
dy_dNTC_B2585 = diff(y, NTC_B2585);
dy_dR1509 = diff(y, R1509);
dy_dR1510 = diff(y, R1510);
dy_dR1507 = diff(y, R1507);
dy_dS3V3S_A = diff(y, S3V3S_A);
dy_dRon = diff(y, Ron);
dy_dLeakageCurrent = diff(y, LeakageCurrent);
dy_dGainError = diff(y, GainError);
dy_dVOLT_REF_3V = diff(y, VOLT_REF_3V);
dy_dOffsetError = diff(y, OffsetError);
dy_dINLError = diff(y, INLError);
dy_dDNLError = diff(y, DNLError);
dy_dS3V3S_A_Ripple = diff(y, S3V3S_A_Ripple);
dy_dPSRR = diff(y, PSRR);
dy_dResolutionADC = diff(y, ResolutionADC);
dy_dR1508 = diff(y, R1508);
dy_dR1511 = diff(y, R1511);
dy_dADC2ADC_GainError = diff(y, ADC2ADC_GainError);
dy_dADC2ADC_OffsetError = diff(y, ADC2ADC_OffsetError);
dy_dADC2ADC_Isolation = diff(y, ADC2ADC_Isolation);
%% Define working points
% Define your working point values
T_NTC_wp1 = 130 + 273.15;
NTC_R_wp1 = 5e3;
NTC_B2585_wp1 = 3420;
R1509_wp1 = 1e3;
R1510_wp1 = 20e3;
R1507_wp1 = 2e3;
S3V3S_A_wp1 = 3.33;
Ron_wp1 = 500;
LeakageCurrent_wp1 = 0;
GainError_wp1 = 0;
OffsetError_wp1 = 0;
VOLT_REF_3V_wp1 = 3;
INLError_wp1 = 0;
DNLError_wp1 = 0;
S3V3S_A_Ripple_wp1 = 10e-3;
PSRR_wp1 = 57;
ResolutionADC_wp1 = 12;
R1508_wp1 = 1e3;
R1511_wp1 = 1e3;
ADC2ADC_GainError_wp1 = 0;
ADC2ADC_OffsetError_wp1 = 0;
ADC2ADC_Isolation_wp1 = 0;
%% Combine working points into a vector
WP1 = [T_NTC_wp1 NTC_R_wp1 NTC_B2585_wp1 R1509_wp1 R1510_wp1 R1507_wp1 S3V3S_A_wp1 Ron_wp1 …
LeakageCurrent_wp1 GainError_wp1 OffsetError_wp1 VOLT_REF_3V_wp1 INLError_wp1 …
DNLError_wp1 S3V3S_A_Ripple_wp1 PSRR_wp1 ResolutionADC_wp1 R1508_wp1 R1511_wp1 …
ADC2ADC_GainError_wp1 ADC2ADC_OffsetError_wp1 ADC2ADC_Isolation_wp1];
%% Calculate sensitivity
symbols = [T_NTC NTC_R NTC_B2585 R1509 R1510 R1507 S3V3S_A Ron LeakageCurrent GainError OffsetError …
VOLT_REF_3V INLError DNLError S3V3S_A_Ripple PSRR ResolutionADC R1508 R1511 ADC2ADC_GainError …
ADC2ADC_OffsetError ADC2ADC_Isolation];
S_NTC_R_wp1 = (subs(dy_dNTC_R, symbols, WP1) * NTC_R_wp1) / subs(y, symbols, WP1)
% S_NTC_R_wp1_num = double(S_NTC_R_wp1);
S_NTC_R_wp1_num = vpa(S_NTC_R_wp1); I have 22 symbolic variables, which I create different subexpressions with. Then I mathematically combine all these subexpression in one big expression according to the calculation I have to perform. I do these steps to keep some readability. However, matlab automatically creates new variables in the final expression, whereby they are named sigmas. When I then substitute numerical values into the symbolic variables, I get a complex result, which I can convert into a double precision number. However, I need to compute the derivative first and then substitute numerical values and at that point I get the error that it is not possible to convert them because symbolic variabls remains in the expression. I suppose that’s because of the new sigma variables. I tried vpa(), double(), simplify() but I do not get it solved. Does someone have an idea how I could handle that ? You can see that the derivative result is displayed with a D if you open the result and not sigma can be seen like it is displayed in the script.
syms T_NTC NTC_R NTC_B2585 R1509 R1510 R1507 S3V3S_A Ron LeakageCurrent GainError OffsetError VOLT_REF_3V INLError DNLError S3V3S_A_Ripple PSRR ResolutionADC
syms R1508 R1511 ADC2ADC_GainError ADC2ADC_OffsetError ADC2ADC_Isolation
%% Resistor network TEMP_DCB
R_NTC = NTC_R.*exp(NTC_B2585*(1./(T_NTC)-1/298.15));
Rs_TEMP_DCB = R1509 + 1./(1./R1510+1./R_NTC+1./R1507);
TEMP_DCB = S3V3S_A.*(R_NTC.*R1510./(R_NTC+R1510))./(R_NTC.*R1510./(R_NTC+R1510)+R1507) + (Rs_TEMP_DCB+Ron).*LeakageCurrent;
ADC_error_TEMP_DCB = GainError.*TEMP_DCB./VOLT_REF_3V + OffsetError + INLError + DNLError + S3V3S_A_Ripple*10.^(-PSRR/20).*2.^ResolutionADC./VOLT_REF_3V;
TEMP_DCB_ADCRawValue = round(TEMP_DCB.*2^ResolutionADC./VOLT_REF_3V + ADC_error_TEMP_DCB);
%% Resistor network 3V3S_A
Rs_VOLT_3V3S_A = R1508.*R1511./(R1508+R1511);
VOLT_3V3S_A = S3V3S_A.*R1511./(R1511+R1508) + (Rs_VOLT_3V3S_A+Ron).*LeakageCurrent;
ADC_error_3V3S_A = (GainError+ADC2ADC_GainError).*VOLT_3V3S_A./VOLT_REF_3V + OffsetError + ADC2ADC_OffsetError + ADC2ADC_Isolation + INLError + DNLError + S3V3S_A_Ripple*10.^(-PSRR/20).*2.^ResolutionADC./VOLT_REF_3V;
VOLT_3V3S_A_ADCRawValue = round(VOLT_3V3S_A.*2^ResolutionADC./VOLT_REF_3V + ADC_error_3V3S_A);
%% Ratio TEMP_DCB/VOLT_3V3S_A
y = TEMP_DCB_ADCRawValue./VOLT_3V3S_A_ADCRawValue
%% Derivatives
dy_dNTC_R = diff(y, NTC_R);
dy_dNTC_B2585 = diff(y, NTC_B2585);
dy_dR1509 = diff(y, R1509);
dy_dR1510 = diff(y, R1510);
dy_dR1507 = diff(y, R1507);
dy_dS3V3S_A = diff(y, S3V3S_A);
dy_dRon = diff(y, Ron);
dy_dLeakageCurrent = diff(y, LeakageCurrent);
dy_dGainError = diff(y, GainError);
dy_dVOLT_REF_3V = diff(y, VOLT_REF_3V);
dy_dOffsetError = diff(y, OffsetError);
dy_dINLError = diff(y, INLError);
dy_dDNLError = diff(y, DNLError);
dy_dS3V3S_A_Ripple = diff(y, S3V3S_A_Ripple);
dy_dPSRR = diff(y, PSRR);
dy_dResolutionADC = diff(y, ResolutionADC);
dy_dR1508 = diff(y, R1508);
dy_dR1511 = diff(y, R1511);
dy_dADC2ADC_GainError = diff(y, ADC2ADC_GainError);
dy_dADC2ADC_OffsetError = diff(y, ADC2ADC_OffsetError);
dy_dADC2ADC_Isolation = diff(y, ADC2ADC_Isolation);
%% Define working points
% Define your working point values
T_NTC_wp1 = 130 + 273.15;
NTC_R_wp1 = 5e3;
NTC_B2585_wp1 = 3420;
R1509_wp1 = 1e3;
R1510_wp1 = 20e3;
R1507_wp1 = 2e3;
S3V3S_A_wp1 = 3.33;
Ron_wp1 = 500;
LeakageCurrent_wp1 = 0;
GainError_wp1 = 0;
OffsetError_wp1 = 0;
VOLT_REF_3V_wp1 = 3;
INLError_wp1 = 0;
DNLError_wp1 = 0;
S3V3S_A_Ripple_wp1 = 10e-3;
PSRR_wp1 = 57;
ResolutionADC_wp1 = 12;
R1508_wp1 = 1e3;
R1511_wp1 = 1e3;
ADC2ADC_GainError_wp1 = 0;
ADC2ADC_OffsetError_wp1 = 0;
ADC2ADC_Isolation_wp1 = 0;
%% Combine working points into a vector
WP1 = [T_NTC_wp1 NTC_R_wp1 NTC_B2585_wp1 R1509_wp1 R1510_wp1 R1507_wp1 S3V3S_A_wp1 Ron_wp1 …
LeakageCurrent_wp1 GainError_wp1 OffsetError_wp1 VOLT_REF_3V_wp1 INLError_wp1 …
DNLError_wp1 S3V3S_A_Ripple_wp1 PSRR_wp1 ResolutionADC_wp1 R1508_wp1 R1511_wp1 …
ADC2ADC_GainError_wp1 ADC2ADC_OffsetError_wp1 ADC2ADC_Isolation_wp1];
%% Calculate sensitivity
symbols = [T_NTC NTC_R NTC_B2585 R1509 R1510 R1507 S3V3S_A Ron LeakageCurrent GainError OffsetError …
VOLT_REF_3V INLError DNLError S3V3S_A_Ripple PSRR ResolutionADC R1508 R1511 ADC2ADC_GainError …
ADC2ADC_OffsetError ADC2ADC_Isolation];
S_NTC_R_wp1 = (subs(dy_dNTC_R, symbols, WP1) * NTC_R_wp1) / subs(y, symbols, WP1)
% S_NTC_R_wp1_num = double(S_NTC_R_wp1);
S_NTC_R_wp1_num = vpa(S_NTC_R_wp1); symbolic, matlab, convert, function, variables MATLAB Answers — New Questions
