In my code we are using a multiplication as (180.00*60.00).
Ideally since both the numbers are of decimal type I'm expecting my answer to be also in decimal. But in redshift I observed that this equation is resulting only to Integer.
Basically when this multiplication happens I want the answer as 10800.0000 and not 10800.
how to achieve this in Redshift. I tried putting the cast to whole expression and also even to individual expression but still I'm getting the answer only in Integer.
any help here?
If I understand your question correctly you are asking why Redshift isn't inferring that the string "180.00*60.00" as being the multiplication of 2 values in decimal type, yes? If correct you just need to cast the input values for the multiplication. For example:
select 180.00::decimal(6,2) * 60.00::decimal(6,2) ;
It also looks like you want the result to have 4 significant digits so you may want to cast to decimal(8,4).
If I've missed the point of your question please clarify.
Related
I am very new to MATLAB. I am sorry if my question is basic. I am using "printmat" function to show some matrices in the command console. For example, printmat(A) and printmat(B), where A = 2.79 and B = 0.45e-7 is a scalar (for the sake of simplicity).
How do I increase the precision arbitrarily to seven decimals? For example: my output looks like 2.7943234 and B = 0.00000004563432.
How do I add a currency (say dollar) figure to the output of printmat?
How do I add a percentage figure (%) to the output of printmat?
Note: The reason I use printmat is that I can name my rows and columns. If you know a better function that can do all above, I would be glad to know.
Regards Mariam. From what I understand, you would like to display the numbers and show their full precision. I am also newbie, If I may contribute, you could convert the number data to string data (for display purposes) by using the sprintf function.
I am using the variable A=2.7943234 as example. This value will not display the full precision, instead it will display 2.7943. To show all the decimal tails, you could first convert this to string by
a = sprintf('%0.8f',A);
It will set the value a to a string '2.79432340'. The %0.8f means you want it to display 8 decimal tails. For this example,%0.7f is sufficient of course.
Another example: A=0.00000004563432, use %0.14f.
A=0.00000004563432;
a=sprintf('%0.14f $ or %%',A);
the output should be : '0.00000004563432 $ or %'.
You could analyze further in https://www.mathworks.com/help/matlab/ref/sprintf.html
You could try this first. If this does not help to reach your objective, I appreciate some inputs. Thanks.
The printmat function is very obsolete now. I think table objects are its intended successor (and functions such as array2table to convert a matrix to a table of data). Tables allow you to add row and column names and format the columns in different ways. I don't think there's a way to add $ or % to each number, but you can specify the units of each column.
In general, you can also format the display precision using format. Something like this may be what you want:
format long
I am trying to write a program in C to get the percent of even numbers in an array. I am thinking of writing it using int datatype. But some one mentioned to me using double will be easier. I don't understand that. Can anyone guide me with it?
What does double datatype return?
Can the return statement be given as return (double)? What will that give?
Can double convert a real number to a percent? Eg: 0.5 to 50.0
The int datatype is, as the name would suggest, integers (or whole numbers). So you cannot represent a decimal like 0.5. A double is decimal number. So you can hold numbers like 0.5. Common practice is to store your percentage as a simple decimal number like 0.5 (using the double type). Then when you need to display nicely as 50.0%, just multiply by 100 before displaying.
Here's a useful link on C's basic datatypes: http://www.tutorialspoint.com/ansi_c/c_basic_datatypes.htm
I want to use xor for my double numbers in matlab,but bitxor is only working for int numbers. Is there a function that could convert double to int in Matlab?
The functions You are looking for might be: int8(number), int16(number), uint32(number) Any of them will convert Double to an Integer, but You must pick the best one for the result You want to achieve. Remember that You cannot cast from Double to Integer without rounding the number.
If I understood You correcly, You could create a function that would simply remove the "comma" from the Double number by multiplying your starting value by 2^n and then casting it to Integer using any of the functions mentioned earlier, performing whatever you want and then returning comma to its original position by dividing the number by 2^n
Multiplying the starting value by 2^n is a hack that will decrease the rounding error.
The perfect value for n would be the number of digits after the comma if this number is relatively small.
Please also specify, why are You trying to do this? This doesn't seem to be the optimal solution.
You can just cast to an integer:
a = 1.003
int8(a)
ans =
1
That gives you an 8 bit signed integer, you can also get other size i.e. int16 or else unsigned i.e. uint8 depending on what you want to do
I'm having some difficulties processing some numbers. The results I get are some like:
0.000093145+1.6437e-011i
0.00009235+4.5068e-009i
I've already try to use format long and as alternative passing to string and then str2num and with no good results also. Although is not being possible to convert them properly as I want (e.g. to a number with 9 decimals) If nobody is able to help me, at least I would appreciate if someone can tell me how to interpret the meaning of the i base.
You are talking about the imaginary unit i. If you are just using real number, you could neglect the imaginary part (it is very small). Thus, try:
real(0.000093145+1.6437e-011i)
After taking real() you can also control the decimal place formatting by sprintf:
sprintf('%0.2f', pi)
Will result in:
'3.14'
Place a 9 instead of a 2 for 9 decimal places.
Many languages have an isNaN() function. I am asking myself: why check for not being a number?
Is the reason purely logical or is it faster to check for not a number instead of is a number?
Note that this is a pure question of understanding. I know that I can negate isNaN() to achieve an isNumber() function for example.
However I am searching for a reason WHY we are checking for not a number?
In computing, NaN (Not a Number) is a
value of numeric data type
representing an undefined or
unrepresentable value, especially in
floating-point calculations.
Wiki Article
Because Not a Number is a special case of an expression.
You can't just use 0 or -1 or something like that because those numbers already have meanings.
Not a Number means something went awry in a calculation and a valid number cannot be computed out of it.
It's on the same line of thinking as having null. Sure, we could assign an arbitrary numerical value to mean null but it would be confusing and we'd hit all sorts of weird errors on corner cases.
'Not a Number' is the result of specific floating point calculations. It's not about "hey, is this variable holding 120 or "abc"?'
isThisCaseExceptional seems more reasonable to me than isEverythingNormal because I'm likely to write
possible_number = some_calculation();
if (inNaN(possible_number)) handle_the_surprise;
// .. keep going
instead of
possible_number = some_calculation();
if (inANumber(possible_number)) {
// .. keep going
} else {
// handle the surprise
}
The check is for whether it is not a number, because the assumption is that it is a number. NaN is the exceptional case when you're expecting a numeric value, so it makes sense to me that it is done this way. I'd rather check for isNaN infrequently than check if a value isNum frequently, after all.
It is a way to report an error condition (mathematically undefined or outside of technical limits).
Many languages have special representations if the result of a computation is not representable by a number, for example NaN and Inf. So isNaN() checks, if a result is actually a number or the special marker for NaN.
NaNs are used for:
Nonreal or undefined values.
Error handling. Initializing a variable with NaN allows you to test for NaN and make sure it has been set with a valid value.
Objects that ignore a member or property. For example, WPF uses NaN to represent the Width and Height of visual elements that do not define their own size.