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### 4.1.3 Constructing floating-point numbers

`cl_F`

objects with low precision are most easily constructed from
C ‘`float`’ and ‘`double`’. See Conversions.

To construct a `cl_F`

with high precision, you can use the conversion
from ‘`const char *`’, but you have to specify the desired precision
within the string. (See Internal and printed representation.)
Example:

cl_F e = "0.271828182845904523536028747135266249775724709369996e+1_40";

will set ‘`e`’ to the given value, with a precision of 40 decimal digits.

The programmatic way to construct a `cl_F`

with high precision is
through the `cl_float`

conversion function, see
Conversion to floating-point numbers. For example, to compute
`e`

to 40 decimal places, first construct 1.0 to 40 decimal places
and then apply the exponential function:

float_format_t precision = float_format(40); cl_F e = exp(cl_float(1,precision));

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