Decreasing digits of answer

Hello,

grad =

I have an output like this, but I want at most 6 digit of numbers. How can I change it? Please help me.

Thank you so much

Answer 1

[Paul]

Try:

vpa(grad,6)

[John Adams]

still same

[Paul]

Can you post the the code that generates grad, or save it to a .mat file and post add it to your question using the paper clip icon. Hard to help without being able to recreate the results.

[John Adams]

syms x y
x1=2.234;
y1=2.24;
x2=5.34;
y2=5.5452;
x3=2.123;
y3=5.153;
x4=3.656;
y4=5.03;
x5=2.6001;
y5=6.253;
x6=1.933;
y6=3.411;
A= [1 x y x^2 x*y y^2]

A = 

B= [1 x1 y1 x1^2 x1*y1 y1^2;1 x2 y2 x2^2 x2*y2 y2^2;1 x3 y3 x3^2 x3*y3 y3^2;
    1 x4 y4 x4^2 x4*y4 y4^2;1 x5 y5 x5^2 x5*y5 y5^2;1 x6 y6 x6^2 x6*y6 y6^2;]

B = 6×6

1.0000 2.2340 2.2400 4.9908 5.0042 5.0176 1.0000 5.3400 5.5452 28.5156 29.6114 30.7492 1.0000 2.1230 5.1530 4.5071 10.9398 26.5534 1.0000 3.6560 5.0300 13.3663 18.3897 25.3009 1.0000 2.6001 6.2530 6.7605 16.2584 39.1000 1.0000 1.9330 3.4110 3.7365 6.5935 11.6349

invB= inv(B)

invB = 6×6

-2.0905 1.3396 -12.3014 -4.8507 7.2358 11.6671 2.2593 -0.8656 3.8676 2.2793 -2.0882 -5.4524 -0.2062 -0.1204 3.8107 0.7954 -2.4315 -1.8479 0.1644 0.1879 0.6403 -0.3728 -0.2535 -0.3663 -0.6349 -0.0427 -1.6263 0.0996 0.7106 1.4938 0.1718 0.0278 0.0135 -0.1317 0.1166 -0.1981

C= A * invB

C = 

It is the simplified code. C goes like this.

[Walter Roberson]

syms x y
x1=2.234;
y1=2.24;
x2=5.34;
y2=5.5452;
x3=2.123;
y3=5.153;
x4=3.656;
y4=5.03;
x5=2.6001;
y5=6.253;
x6=1.933;
y6=3.411;
A= [1 x y x^2 x*y y^2]

A = 

B= [1 x1 y1 x1^2 x1*y1 y1^2;1 x2 y2 x2^2 x2*y2 y2^2;1 x3 y3 x3^2 x3*y3 y3^2;
    1 x4 y4 x4^2 x4*y4 y4^2;1 x5 y5 x5^2 x5*y5 y5^2;1 x6 y6 x6^2 x6*y6 y6^2;]

B = 6×6

1.0000 2.2340 2.2400 4.9908 5.0042 5.0176 1.0000 5.3400 5.5452 28.5156 29.6114 30.7492 1.0000 2.1230 5.1530 4.5071 10.9398 26.5534 1.0000 3.6560 5.0300 13.3663 18.3897 25.3009 1.0000 2.6001 6.2530 6.7605 16.2584 39.1000 1.0000 1.9330 3.4110 3.7365 6.5935 11.6349

invB= inv(B)

invB = 6×6

-2.0905 1.3396 -12.3014 -4.8507 7.2358 11.6671 2.2593 -0.8656 3.8676 2.2793 -2.0882 -5.4524 -0.2062 -0.1204 3.8107 0.7954 -2.4315 -1.8479 0.1644 0.1879 0.6403 -0.3728 -0.2535 -0.3663 -0.6349 -0.0427 -1.6263 0.0996 0.7106 1.4938 0.1718 0.0278 0.0135 -0.1317 0.1166 -0.1981

C= A * invB

C = 

vpa(C,6)

ans = 

[Walter Roberson]

But what I suspect you are looking for is

digits(6)
FPO = sympref('floatingpointoutput', true);

syms x y
x1=2.234;
y1=2.24;
x2=5.34;
y2=5.5452;
x3=2.123;
y3=5.153;
x4=3.656;
y4=5.03;
x5=2.6001;
y5=6.253;
x6=1.933;
y6=3.411;
A= [1 x y x^2 x*y y^2]

A = 

B= [1 x1 y1 x1^2 x1*y1 y1^2;1 x2 y2 x2^2 x2*y2 y2^2;1 x3 y3 x3^2 x3*y3 y3^2;
    1 x4 y4 x4^2 x4*y4 y4^2;1 x5 y5 x5^2 x5*y5 y5^2;1 x6 y6 x6^2 x6*y6 y6^2;]

B = 6×6

1.0000 2.2340 2.2400 4.9908 5.0042 5.0176 1.0000 5.3400 5.5452 28.5156 29.6114 30.7492 1.0000 2.1230 5.1530 4.5071 10.9398 26.5534 1.0000 3.6560 5.0300 13.3663 18.3897 25.3009 1.0000 2.6001 6.2530 6.7605 16.2584 39.1000 1.0000 1.9330 3.4110 3.7365 6.5935 11.6349

invB= inv(B)

invB = 6×6

-2.0905 1.3396 -12.3014 -4.8507 7.2358 11.6671 2.2593 -0.8656 3.8676 2.2793 -2.0882 -5.4524 -0.2062 -0.1204 3.8107 0.7954 -2.4315 -1.8479 0.1644 0.1879 0.6403 -0.3728 -0.2535 -0.3663 -0.6349 -0.0427 -1.6263 0.0996 0.7106 1.4938 0.1718 0.0278 0.0135 -0.1317 0.1166 -0.1981

C= A * invB

C = 

sympref('floatingpointoutput', FPO)    %restore setting

ans = logical
   1

[John Adams]

Thanks a lot. :)

[John Adams]

I realized that when I change the number inside of digits(6) or vpa(C,6) answer always starts with 0.1644 why is it like that? Even, Digits = 32 is shown in command window answer has 4 digits

[Walter Roberson]

The sympref always uses 4. I misled when I showed digits(6) as if it controlled the output digits for the sympref

[Paul]

To be clear, 'floatingpointoutput' = true only affects the display of results, not the results themselves.